Washington (CNN) Defense Secretary James Mattis resigned Thursday on the heels of President Donald Trump's plans to withdraw troops from Syria, citing irreconcilable policy differences in a move that took Washington by surprise.

"Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position," Mattis wrote in his letter to the President

Earlier Thursday, a senior administration official told CNN's Jake Tapper that Mattis was "vehemently opposed" to the Syria decision and a possible Afghanistan troop withdrawal.

Indeed, Mattis' resignation letter amounts to a rebuke of several of Trump's foreign policy views, with the outgoing defense secretary touting the importance of US alliances and of being "unambiguous" in approaching adversaries such as Russia and China. It is devoid of any praise for the President.

The resignation emerged at a chaotic moment in Trump's presidency: The US government is teetering on the edge of a government shutdown, the Trump administration is about to face the hot light of Democratic investigations and the President is grappling with the fallout of a series of firings and resignations. Trump, seeking to downplay the news, stepped out in front of Mattis' resignation, spinning it as a retirement.

Mattis did not explicitly cite his opposition to the President's planned withdrawal of US troops from Syria -- which caught US allies off guard -- but the retired four-star general was privately adamant in urging Trump against the pullback.

'They had differences'

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It was just the latest issue on which Mattis has sought to position himself as a bulwark against some of the President's rashest decisions, but his relationship with the President has grown increasingly fractured in recent months and his efforts to deter Trump on key issues less influential.

In his letter, Mattis pointedly stated that the strength of the US depends in part on the strength of its alliances around the globe, many of which have become notably frayed under Trump.

"One core belief I have always held is that our strength as a nation is inextricably linked to the strength of our unique and comprehensive system of alliances and partnerships. While the US remains the indispensable nation in the free world, we cannot protect our interests or serve that role effectively without maintaining strong alliances and showing respect to those allies," he added.

Mattis met with Trump one-on-one in the Oval Office, a senior White House official told CNN's Kaitlan Collins. Mattis told Trump he was going to be leaving and offered his resignation letter.

"They had differences on some issues," the official said.

Trump announced Mattis' departure in a tweet, saying, "General Jim Mattis will be retiring, with distinction, at the end of February, after having served my Administration as Secretary of Defense for the past two years."

The President touted the "tremendous progress" that has been made during Mattis' tenure at the helm of the Defense Department and thanked him for his service.

Trump said a successor "will be named shortly."

In a sign of the swift nature of the resignation, senior White House officials found out about it from the President's tweet, according to two officials. A senior administration official could not say if armed forces were told before the tweet.

Syria decision

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Mattis' resignation comes just a day after the President ordered the "full" and "rapid" withdrawal of US troops from Syria over the objections of Mattis, other senior officials and scores of lawmakers, who declared it a strategic blunder.

The announcement of his departure comes just over an hour after reports emerged that Trump may also be considering a drawdown of US troops in Afghanistan. Sources told CNN's Jake Tapper that the President has not yet made a final decision, but officials are concerned and convinced that he might do so, and soon.

Mattis is the latest senior administration to leave Trump's Cabinet, after former Attorney General Jeff Sessions was pushed out the day after the midterm elections in November, former Secretary of State Rex Tillerson was unceremoniously fired in March and national security adviser H.R. McMaster was replaced earlier this year.

But reaction to Mattis' departure was strikingly different.

In a statement, Senate Majority Leader Mitch McConnell emphasized the importance of maintaining "the post-World War II alliances" as well as "a clear-eyed understanding of our friends and foes."

"So I was sorry to learn that Secretary Mattis, who shares those clear principles, will soon depart the administration," the statement said. "But I am particularly distressed that he is resigning due to sharp differences with the president on these and other key aspects of America's global leadership.

"It is regrettable that the president must now choose a new Secretary of Defense. But I urge him to select a leader who shares Secretary Mattis's understanding of these vital principles and his total commitment to America's servicemembers."

Virginia Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee, tweeted, "This is scary. Secretary Mattis has been an island of stability amidst the chaos of the Trump administration."

South Carolina Republican Sen. Lindsey Graham, a strong Trump supporter who opposes the President's decision to pull out of Syria, expressed "great sadness" over Mattis' resignation.

"He is one of the great military leaders in American history. He should be proud of the service he has rendered to President Trump and our nation," Graham tweeted.

Former Vice President Joe Biden tweeted that despite some disagreements with Mattis, "we shared the view — long-held by Democrats and Republicans in this nation — that respect for our allies and a commitment to the most important and effective alliances in history made America safer."

"It is clear this administration has abandoned those core American beliefs," Biden added . "Secretary Mattis' presence and his voice of reason and experience will be missed in the Pentagon and the Situation Room."

'A good guy'

Mattis' future was brought into question most recently after Trump, in an October interview with CBS' "60 Minutes," labeled him as "sort of a Democrat," adding that the retired general "may leave" and that "at some point, everybody leaves."

He also added that the 68-year-old Washington native was "a good guy" and the two had "a very good relationship."

Mattis, a bachelor, has been described as a "warrior monk," married to the Marines. He served in the first Gulf War and in Afghanistan. He once led the all-important US Central Command, which is in charge of the US military in the Middle East. He was also supreme allied commander of NATO.

After the 2016 election, Trump broke with protocol by tapping Mattis to be his secretary of defense, a position typically reserved for civilians.

In his first six months in office, Trump oversaw a steady transfer of power from the White House to the Pentagon, handing off several war-fighting authorities that previously rested in his hands -- and those of past presidents of both parties -- to the Pentagon and the commanders overseeing the US' military campaigns.

But while Mattis was widely considered one of Trump's most trusted advisers during his first year in office, his influence within the administration appeared to be waning in recent months as speculation swirled about a growing rift between the two men.

Bob Woodward's book "Fear: Trump in the White House," published in September, fueled that notion, detailing how senior aides, including Mattis, grew exasperated with the President and increasingly worried what they described as his erratic behavior, ignorance and penchant for lying.

Specifically, Woodward details several instances in which Mattis made disparaging comments about Trump and military actions he sought to take against Syria and North Korea.

One of the most striking accounts, according to Woodward, occurred after a charged meeting about South Korea, during which Trump wondered why the US backs Seoul. Woodward wrote that Mattis said Trump understands issues at the level of an elementary school student.

Mattis denied those assertions and the accounts detailed by Woodward's sources, including claims that he ignored or slow-rolled Trump's ideas.</s>The retired Marine Corps general, who was known as a stabilising force in President Donald Trump's Cabinet, will retire in February. He becomes the latest in a long list of high ranking Trump administration figures who have either quit or been fired. Mr Trump delivered the news via Twitter.

‘Trump unbound’ President will be EVEN TOUGHER after firing Sessions

He said General Mattis would be retiring with "distinction" and thanked him for his service.

The announcement comes just a day after President Trump announced he had ordered the withdrawal of US forces from Syria - a move opposed by top military officials.

In his resignation letter, General Mattis said he was stepping down so Mr Trump could have a defence chief whose views align more closely with his own.

Speculation that he may not last long in his post grew in October when President Trump said in a CBS interview that the general was "sort of a Democrat" and might be leaving.</s>WASHINGTON (Reuters) - U.S. Defense Secretary Jim Mattis abruptly said he was quitting on Thursday after falling out with President Donald Trump over his foreign policies, including surprise decisions to yank troops from Syria and start planning a drawdown in Afghanistan.

Mattis announced plans to depart in a candid resignation letter to Trump that laid bare the growing divide between them, and implicitly criticized Trump for failing to value America’s closest allies, who fought alongside the United States in both conflicts.

He released the letter after a face-to-face meeting with Trump in which the two men also aired their differences, a senior White House official said.

“Because you have a right to a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position,” Mattis said in the letter.

U.S. officials said the resignation had not been forced by Trump.

Trump announced on Wednesday that U.S. troops in Syria would be withdrawn, a decision that upended American policy in the region. On Thursday, an official said the president was planning to withdraw at least 5,000 of the 14,000 U.S. troops in Afghanistan - another blow to Mattis, who advocated for a strong U.S. military presence to bolster diplomatic peace efforts.

Mattis, a retired Marine general whose embrace of NATO and America’s traditional alliances often put him at odds with Trump had advised against the Syria withdrawal. One official said it was a contributing factor to his resignation.

The news is certain to shock U.S. military allies, already bewildered by what they see as Trump’s unpredictable, go-it-alone approach to global security, and raises questions about whether Mattis’ successor will be as steadfast about traditional treaty commitments, including to NATO.

When Mattis interviewed with Trump for the job in 2016, he split with the president-elect on a host of issues, including on NATO and the use of torture. Trump ultimately deferred to Mattis, who opposed the latter, signaling that he could be persuaded by his advisers.

But as time grew, Trump increasingly acted on his own instincts on a host of national security issues, choosing an “America First” agenda that contradicted Mattis’ core beliefs.

Mattis’ letter indicated that he disagreed with Trump’s isolationist policies, writing that it was his belief the United States needed to maintain strong alliances and show allies respect.

Trump has withdrawn the United States from several international agreements since taking office in January 2017.

The Mattis resignation letter also said that he believed the United States “must be resolute and unambiguous in our approach to those countries whose strategic interests are increasingly in tension with ours.” He identified Russia and China as countries that “want to shape a world consistent with their authoritarian model.”

Mattis’ resignation was greeted with regret on Capitol Hill, by both Republicans and Democrats.

U.S. Senate Majority Leader Mitch McConnell indicated he was in agreement with Mattis on America’s alliances and on Russia, whom he described as a foe.

“But I am particularly distressed that he is resigning due to sharp differences with the president on these and other key aspects of America’s global leadership,” McConnell said in a statement.

U.S. Defense Secretary James Mattis listens as U.S. President Donald Trump speaks to the news media while gathering for a briefing from his senior military leaders in the Cabinet Room at the White House in Washington, U.S., October 23, 2018. REUTERS/Leah Millis

Senator Bob Menendez, the top Democrat on the Foreign Relations Committee, called it “a significant loss and a real indication that President Trump’s foreign policy agenda has failed and continues to spiral into chaos.”

WHITE HOUSE UNPREDICTABILITY

The shifts in significant aspects of U.S. foreign policy and Mattis’ addition to the long list of senior Trump administration figures who have quit or been removed added to the sense of an increasingly unpredictable White House as Trump approaches the halfway point of his four-year term.

And if defense policy disagreements were not enough distraction for a president who is under investigation by a special counsel over Russian interference in the 2016 U.S. election, financial markets took a beating this week and a U.S. government shutdown loomed because of funding disputes over Trump’s desire to build a wall on the U.S.-Mexico border.

This year has been the worst for world stock markets since the 2008 global financial crisis, with MSCI’s 47-country world stocks index down 10 percent.

Trump, announcing Mattis’ departure on Twitter, said he would nominate a successor soon.

“General Jim Mattis will be retiring, with distinction, at the end of February, after having served my Administration as Secretary of Defense for the past two years,” he said.

One possible candidate to replace Mattis as defense chief could be Republican Senator Tom Cotton, long considered a front-runner to eventually take the role.

Trump’s White House has had the highest turnover of senior-level staff of the past five presidents, according to the Brookings Institution think tank.

Slideshow (6 Images)

Some departed unceremoniously, such as Trump’s first Secretary of State Rex Tillerson, whom Trump fired via Twitter in March.

Speculation that Mattis might not last long in his post grew in October when Republican Trump said in a CBS interview that the general was “sort of a Democrat” and might be leaving. Mattis responded at the time by telling reporters that he had Trump’s full support.

Stephen Miller, a senior White House adviser, said Trump was entitled to a Pentagon chief with whom he could agree.

“This is an opportunity for the whole country to get a new secretary of defense who will be aligned with the president on these critical issues, whether you’re talking about in Syria, whether you’re talking about across the Middle East in general,” Miller told CNN.</s>US Defence Secretary Jim Mattis will be “retiring, with distinction,” in February, President Donald Trump has said, a day after he ordered American troops to rapidly withdraw from war-torn Syria in an abrupt decision criticised by many as premature.

In his resignation letter sent on Thursday, Mattis told Trump it was the “right time” for him to step down because the US president deserved a defence secretary “whose views are better aligned with yours on these and other subjects.”

“The end date for my tenure is February 28, 2019, a date that should allow sufficient time for a successor to be nominated and confirmed as well as to make sure the Department’s interests are properly articulated and protected at upcoming events to include Congressional posture hearings and the NATO Defense Ministerial meeting in February,” he said.

The 68-year-old Pentagon chief did not mention if he was resigning specifically over the troop withdrawal decision, which has surprised US allies and several lawmakers.

Analysts say the withdrawal of troops will please US enemies by clearing the way for Syria’s Assad regime, Russia and Iran. Mattis had warned that removing ground forces from the Middle Eastern country would be a “strategic blunder”.

After Mattis sent his resignation, Trump announced he will be “retiring” in February.

“General Jim Mattis will be retiring, with distinction, at the end of February, after having served my administration as secretary of defense for the past two years,” the president said.

“During Jim’s tenure, tremendous progress has been made, especially with respect to the purchase of new fighting…,” he said.

Mattis has been a great advocate of India-US defence relationship.

Earlier this month, he had hosted Defence Minister Nirmala Sitharaman at the Pentagon for talks on India-US Defence relationship. “The US-India relationship is a natural partnership between the world’s oldest and the world’s largest democracy,” Mattis had said then.

Mattis and Trump reportedly have had differences on several foreign policy issues, including Syria and Afghanistan. Reports say the president is considering a drawdown of US troops from the 17-year-long conflict in Afghanistan.

He is the latest in long-list of senior Trump administration official to leave or removed. In March, Trump fired Secretary of State Rex Tillerson in an announcement on Twitter.

On Thursday however, Trump praised Mattis for his service and for being a “great help” to him in getting allies and other countries “to pay their share of military obligations”.

He said a new secretary of defence will be named shortly.

A day before, Trump had claimed in a tweet that the US has “defeated” the Islamic State terrorist group in Syria. The White House afterwards insisted that the main objective of American forces in the war-torn country was to destroy the ISIS and not to resolve the civil war.

But analysts and US lawmakers were far from convinced about the abrupt decision, which was also a reversal of the stated US policy. It has attracted criticism from leaders of Trump’s own Republican party, who argued that the hasty decision would endanger American national security in the long run.

Republican Senator Marco Rubio said the full and rapid withdrawal of US troops from Syria is a grave error with broader implications beyond just the fight against the ISIS group.

Currently, there are about 2,000 US forces in Syria.

Also, Mattis said in his resignation letter that he believes the US must be resolute in its approach to countries whose strategic interests are increasingly in tension with America’s.

“My views on treating allies with respect and also being clear-eyed about both malign actors and strategic competitors are strongly held and informed by over four decades of immersion in these issues,” he stressed.

“We must do everything possible to advance an international order that is most conducive to our security, prosperity and values, and we are strengthened in this effort by the solidarity of our alliances,” he added.

Defending his decision on Thursday to withdraw from Syria, Trump had tweeted that the US does not want to be the “policeman” of the Middle East. In his resignation letter, Mattis said, “Like you, I have said from the beginning that the armed forces of the United States should not be the policeman of the world.

“Instead, we must use all tools of American power to provide for the common defense, including providing effective leadership to our alliances.”</s>Yet another member of the Trump administration has quit, with the president announcing on December 20 that Secretary of Defense Jim Mattis will retire at the end of February 2019. We have more details here.

“General Jim Mattis will be retiring, with distinction, at the end of February, after having served my Administration as Secretary of Defense for the past two years,” President Donald Trump tweeted on December 20. “During Jim’s tenure, tremendous progress has been made, especially with respect to the purchase of new fighting……..equipment. General Mattis was a great help to me in getting allies and other countries to pay their share of military obligations. A new Secretary of Defense will be named shortly. I greatly thank Jim for his service!”

Mattis’ resignation letter was made public shortly after Trump’s surprise announcement. His departure comes one day after Trump announced that the United States would be withdrawing 2000 troops from Syria, over the objections of senior military officials, and while the letter doesn’t name Syria specifically, it’s clear that he’s leaving the administration over the decision. It reads, in part, “My views on treating allies with respect and also being clear-eyed about both malign actors and strategic competitors are strongly held and informed by over four decades of immersion on these issues… Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position.”

Trump and Mattis have butted heads lately, with the president calling the secretary a “Democrat” in October during an interview with 60 Minutes, during which he also predicted Mattis’ departure. “General Mattis is a good guy,” he said. “We get along very well. He may leave. I mean, at some point, everybody leaves. Everybody. People leave. That’s Washington.” It was reported in September that Mattis and former Chief of Staff John Kelly, who also just quit, mocked the president behind his back. They allegedly called him an idiot and said that DC was a “crazytown.”

Obviously, Twitter is losing it over the umpteenth member of the Trump administration splitting. “Seems Mad dog Mattis is`nt mad enough to take the Donald on. retireing [sic] in Feb 19 You see Trump, god bless him, is really Mad. they don’t lose fights. so all you snowflakes out there be more deserning [sic] before you start a fight, you might pick on the wrong madman?” Another critic joked, “Uhhmmm… really? Mattis resignation letter, I’ll break it down for you. Trump you are an a**hole.” And another chimed in with a very good point: “Oh, my, and now I’ve read the Mattis letter. Trump didn’t understand what he read when he first saw it, that’s why his tweet is coherent and sane. Once Fox News explains to him that Mattis called him a traitorous twatwaffle he’s really gonna hit the roof.”</s>WASHINGTON (AP) — President Donald Trump has announced that Defense Secretary Jim Mattis will retire at the end of February.

Trump says on Twitter that a new secretary of defense will be named soon.

Trump's announcement comes a day after he surprised U.S. allies and members of Congress by announcing the withdrawal of U.S. troops from Syria.</s>(CNN) — Defense Secretary Jim Mattis will step down from his position early next year, President Donald Trump announced Thursday evening.

“General Jim Mattis will be retiring, with distinction, at the end of February, after having served my Administration as Secretary of Defense for the past two years,” Trump tweeted.

Trump touted the “tremendous progress” that has been made during Mattis’ tenure at the helm of the Defense Department and thanked Mattis for his service.

Trump announced Mattis’ exit a day after his plans to withdraw troops from Syria became public, a decision that Mattis and the President’s other top national security advisers opposed.

In a resignation letter from Mattis, Mattis said his views don’t “align” with the President’s.

“Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position,” Mattis wrote in his letter.

“One core belief I have always held is that our strength as a nation is inextricably linked to the strength of our unique and comprehensive system of alliances and partnerships. While the US remains the indispensable nation in the free world, we cannot protect our interests or serve that role effectively without maintaining strong alliances and showing respect to those allies,” he added.</s>WASHINGTON – President Donald Trump announced Thursday that Defense Secretary Jim Mattis would leave the Pentagon at the end of February.

The announcement came amid the two butting heads on the removal of U.S. troops from Syria, a key policy the president announced on Twitter Wednesday. The president said Mattis, 68, was retiring, but a letter from Mattis shows he resigned so the president could have a defense secretary "whose views are better aligned with yours."

In his resignation letter, Mattis also took a swipe at a tweet posted by the president on Thursday in which he defended his decision to withdraw 2,000 troops from Syria. America, Trump tweeted, should not act as the world’s "policeman."

“Like you, I have said from the beginning that the armed forces of the United States should not be the policeman of the world,” Mattis wrote. “Instead, we must use all the tools of American power to provide for the common defense, including providing effective leadership to our alliances.”

More: Defense Secretary Jim Mattis leaving his job after clash with Trump over Syria</s>
• Secretary of Defense Jim Mattis is stepping down, and his resignation letter released on Thursday offers some insight about what motivated his decision.
• "Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position," he continued.

Secretary of Defense Jim Mattis is leaving the White House and his resignation letter released to news organizations on Thursday give insight into why.

"My views on treating allies with respect and also being clear-eyed about both malign actors and strategic competitors are strongly held and informed by over four decades of immersion in these issues," Mattis, a retired four-star Marine Corps general wrote . "We must do everything possible to advance an international order that is most conducive to our security, prosperity and values, and we are strengthened in this effort by the solidarity of our alliances."

"Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position," he continued. The full letter can be read below:

According to the letter, Mattis will leave his post on February 28, 2019, "a date that should allow sufficient time for a successor to be nominated and confirmed," he wrote in his letter. Mattis served for 44 years in the US Marine Corps, and in his letter he expressed his appreciation for "this opportunity to serve the nation and our men and women in uniform."

Read more: Defense Secretary Jim Mattis quits, says his views aren't 'aligned' with Trump as president upends major US policies

On Thursday, President Donald Trump tweeted that Mattis was "retiring, with distinction, at the end of February."

"General Jim Mattis will be retiring, with distinction, at the end of February, after having served my Administration as Secretary of Defense for the past two years. During Jims tenure, tremendous progress has been made, especially with respect to the purchase of new fighting equipment," Trump said in a tweet. "General Mattis was a great help to me in getting allies and other countries to pay their share of military obligations. A new Secretary of Defense will be named shortly. I greatly thank Jim for his service!"

The announcement about Mattis leaving his post comes one day after Trump announced a withdrawal of troops from Syria on Wednesday, a decision that allegedly surprised the Pentagon and drew ire from Republican lawmakers on Capitol Hill .

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• Trump just radically upended US Syria policy despite repeated warnings that doing so could be disastrous
• Trump outright ignored Pentagon, State Department Syria policy in a big win for Putin
• Trump declares victory over ISIS as the US prepares to pull all troops out of Syria

SEE ALSO: 17 of the most legendary quotes from James Mattis, the four-star Marine general who just resigned as Trump's Defense Secretary</s>WASHINGTON: Defence Secretary James Mattis has resigned, telling Donald Trump in a letter that he should choose a person who is more in tune with his world view after the US president decided to withdraw American troops from Syria.

Trump announced the resignation in two tweets on Thursday evening, and said Mattis, will leave at the end of February. Mattis was a great advocate of India-US defence relationship.

According to reports, 68-year-old Mattis went to the White House on Thursday afternoon in a last attempt to convince Trump to keep US troops in Syria. He was rebuffed, and told the president that he was resigning as a result.

In his extraordinary resignation letter, Mattis told Trump he had “the right to have a Secretary of Defence whose views are better aligned with yours”.

Mattis’ resignation letter, a Pentagon spokeswoman said was hand-delivered to the president.

In the letter, Mattis told Trump it was the “right time” for him to step down.

“The end date for my tenure is February 28, 2019, a date that should allow sufficient time for a successor to be nominated and confirmed as well as to make sure the Department’s interests are properly articulated and protected at upcoming events to include Congressional posture hearings and the NATO Defense Ministerial meeting in February,” Mattis said.

The Pentagon chief did not mention if he was resigning specifically over the troop withdrawal decision, which has surprised US allies and several lawmakers.

Analysts say the withdrawal of troops will please US enemies by clearing the way for Syria’s Bashar al-Assad regime, Russia and Iran. Mattis had warned that removing ground forces from the Middle Eastern country would be a “strategic blunder”. Currently, there are about 2,000 US forces in Syria.

After Mattis sent his resignation, Trump said, “General Jim Mattis will be retiring, with distinction, at the end of February, after having served my administration as secretary of defense for the past two years.

“During Jim’s tenure, tremendous progress has been made, especially with respect to the purchase of new fighting…,” he said on Twitter.

Mattis and Trump reportedly have had differences on several foreign policy matters, including Syria and Afghanistan. Reports say the president is also considering a drawdown of US troops from the 17-year-long conflict in Afghanistan.

Mattis said in his resignation letter that he believes the US must be resolute in its approach to countries whose strategic interests are increasingly in tension with America’s.

“My views on treating allies with respect and also being clear-eyed about both malign actors and strategic competitors are strongly held and informed by over four decades of immersion in these issues,” he stressed.

“We must do everything possible to advance an international order that is most conducive to our security, prosperity and values, and we are strengthened in this effort by the solidarity of our alliances,” he added.

Mattis is the latest in long-list of senior Trump administration officials to leave or be removed. In March, Trump fired Secretary of State Rex Tillerson.

On Thursday, Trump praised Mattis for his service and for being a “great help” to him in getting allies and other countries “to pay their share of military obligations”.

He said a new secretary of defence will be named shortly.

Defending his decision on Thursday to withdraw US troops from Syria, Trump tweeted that the US does not want to be the “policeman” of the Middle East. In his resignation letter, Mattis said, “Like you, I have said from the beginning that the armed forces of the United States should not be the policeman of the world.

“Instead, we must use all tools of American power to provide for the common defence, including providing effective leadership to our alliances.”

Mattis’ celebrated military career spanned four decades. Prior to joining Trump’s Cabinet, the four-star general was the head of US Central Command, which directs military operations and oversaw the wars in Iraq and Afghanistan.

He was known before and during his White House tenure for his even-keeled demeanour and strategic mind and is broadly held in high esteem among Republicans and Democrats alike.

“I’m shaken by the news because of the patriot that Secretary Mattis is,” said House Minority Leader Nancy Pelosi. PTI
U.S. Secretary of Defence Jim Mattis announces his resignation at the end of February 2019. Mattis says that his views are not well "aligned" with those of the President.