In a January 2017 phone call with Saudi Arabia's deputy crown prince Mohammed bin Salman, Mattis "reaffirmed the importance of the US–Saudi Arabia strategic relationship".

For his first official trip abroad, Mattis began a two-day visit with longtime US ally South Korea on February 2, 2017.
He warned North Korea that "any attack on the United States, or our allies, will be defeated", and any use of nuclear weapons would be met with an "effective and overwhelming" response from the United States.
During a press conference in London on March 31, 2017 with the British secretary of state for defence, Michael Fallon, Mattis said North Korea was behaving "in a very reckless manner" and must be stopped.
During a Pentagon news conference on May 26, Mattis reported the US was working with the UN, China, Japan, and South Korea to avoid "a military solution" with North Korea.
On June 3 Mattis said the United States regarded North Korea as "clear and present danger" during a speech at the international security conference in Singapore.
In a June 12 written statement to the House Armed Services Committee Mattis said North Korea was the "most urgent and dangerous threat to peace and security".
On June 15 Mattis said the US would win a war against North Korea, but "at great cost".

On March 22, 2017, during questioning from the US Senate, Mattis affirmed his support for US troops remaining in Iraq after the Battle of Mosul was concluded.
Mattis responded to critics who suggested the Trump administration had loosened the rules of engagement for the US military in Iraq after US-led coalition airstrikes in Mosul killed civilians, saying, "We go out of our way to always do everything humanly possible to reduce the loss of life or injury among innocent people."
According to Airwars, the US-led coalition killed as many as 6,000 civilians in Iraq and Syria in 2017.

On April 5, 2017, Mattis called the Khan Shaykhun chemical attack "a heinous act," and said it would be treated accordingly.
On April 10 Mattis warned the Syrian government against using chemical weapons again.
The following day, Mattis gave his first Pentagon news conference since becoming secretary of defense, saying ISIL's defeat remained "our priority," and the Syrian government would pay a "very, very stiff price" for further usage of chemical weapons.
On April 21 Mattis said Syria still had chemical weapons and was in violation of United Nations Security Council resolutions.
According to investigative journalist Bob Woodward, Trump ordered Mattis to assassinate Assad, but Mattis refused.
On May 8 Mattis told reporters details of the proposed Syrian safe zones were "all in process right now" and the United States was involved with configuring them.

Mattis voiced support for a Saudi Arabian-led military campaign against Yemen's Shiite rebels.
He asked Trump to remove restrictions on US military support for Saudi Arabia.

On April 20, 2017, one week after the Nangarhar airstrike, Mattis told reporters that the US would not conduct a damage assessment "in terms of the number of people killed" in Afghanistan.
Mattis traveled to Afghanistan days later and met with government officials, explaining that the purpose of the trip was to allow him to state his recommendations for US strategy in the country.
On June 13, Mattis said US forces were "not winning" in Afghanistan and the administration would develop a new strategy by "mid-July" while speaking to the United States Senate Committee on Armed Services.
On June 27 Mattis told reporters that he was creating a conflict-ending strategy for Afghanistan that would also "remove the danger to the Afghan people and to us and to all the nations that have been attacked by terrorist groups out of that region".
On June 29 Mattis said the Obama administration "may have pulled our troops out too rapidly" and that he intended to submit a new Afghanistan strategy to Trump upon his return to Washington, D.C.
The United States has been openly arming the Syrian Kurdish fighters in the war against ISIL since May 2017.
Following the start of the Turkish
In a January 2017 phone call with Saudi Arabia's deputy crown prince Mohammed bin Salman, Mattis "reaffirmed the importance of the US–Saudi Arabia strategic relationship".
For his first official trip abroad, Mattis began a two-day visit with longtime US ally South Korea on February 2, 2017. He warned North Korea that "any attack on the United States, or our allies, will be defeated", and any use of nuclear weapons would be met with an "effective and overwhelming" response from the United States. During a press conference in London on March 31, 2017 with the British secretary of state for defence, Michael Fallon, Mattis said North Korea was behaving "in a very reckless manner" and must be stopped. During a Pentagon news conference on May 26, Mattis reported the US was working with the UN, China, Japan, and South Korea to avoid "a military solution" with North Korea. On June 3 Mattis said the United States regarded North Korea as "clear and present danger" during a speech at the international security conference in Singapore. In a June 12 written statement to the House Armed Services Committee Mattis said North Korea was the "most urgent and dangerous threat to peace and security". On June 15 Mattis said the US would win a war against North Korea, but "at great cost".
On March 22, 2017, during questioning from the US Senate, Mattis affirmed his support for US troops remaining in Iraq after the Battle of Mosul was concluded. Mattis responded to critics who suggested the Trump administration had loosened the rules of engagement for the US military in Iraq after US-led coalition airstrikes in Mosul killed civilians, saying, "We go out of our way to always do everything humanly possible to reduce the loss of life or injury among innocent people." According to Airwars, the US-led coalition killed as many as 6,000 civilians in Iraq and Syria in 2017.
On April 5, 2017, Mattis called the Khan Shaykhun chemical attack "a heinous act," and said it would be treated accordingly. On April 10 Mattis warned the Syrian government against using chemical weapons again. The following day, Mattis gave his first Pentagon news conference since becoming secretary of defense, saying ISIL's defeat remained "our priority," and the Syrian government would pay a "very, very stiff price" for further usage of chemical weapons. On April 21 Mattis said Syria still had chemical weapons and was in violation of United Nations Security Council resolutions. According to investigative journalist Bob Woodward, Trump ordered Mattis to assassinate Assad, but Mattis refused. On May 8 Mattis told reporters details of the proposed Syrian safe zones were "all in process right now" and the United States was involved with configuring them.
Mattis voiced support for a Saudi Arabian-led military campaign against Yemen's Shiite rebels. He asked Trump to remove restrictions on US military support for Saudi Arabia.
On April 20, 2017, one week after the Nangarhar airstrike, Mattis told reporters that the US would not conduct a damage assessment "in terms of the number of people killed" in Afghanistan. Mattis traveled to Afghanistan days later and met with government officials, explaining that the purpose of the trip was to allow him to state his recommendations for US strategy in the country. On June 13, Mattis said US forces were "not winning" in Afghanistan and the administration would develop a new strategy by "mid-July" while speaking to the United States Senate Committee on Armed Services. On June 27 Mattis told reporters that he was creating a conflict-ending strategy for Afghanistan that would also "remove the danger to the Afghan people and to us and to all the nations that have been attacked by terrorist groups out of that region". On June 29 Mattis said the Obama administration "may have pulled our troops out too rapidly" and that he intended to submit a new Afghanistan strategy to Trump upon his return to Washington, D.C.
The United States has been openly arming the Syrian Kurdish fighters in the war against ISIL since May 2017. Following the start of the Turkish 
Jim Mattis