SEOUL/WASHINGTON (Reuters) - Two U.S. strategic bombers conducted drills over South Korea, the U.S. Air Force said, raising tensions with North Korea just days before President Donald Trump visits the region seeking to shut down Pyongyang’s nuclear program. 
 
 A U.S. Air Force B-1B Lancer assigned to the 37th Expeditionary Bomb Squadron, takes-off to fly a bilateral mission with Japanese and South Korea Air Force jets in the vicinity of the Sea of Japan, from Andersen Air Force Base, Guam, October 10, 2017. Senior Airman Jacob Skovo-Lane/U.S. Air Force/Handout via REUTERS 
 
 News of the Thursday’s drills was first reported by North Korean state news agency KCNA on Friday, which said the exercises involving South Korean and Japanese fighter jets were a “surprise nuclear strike drill”. 
 
 “The reality clearly shows that the gangster-like U.S. imperialists are the very one who is aggravating the situation of the Korean peninsula and seeking to ignite a nuclear war,” KCNA said. 
 
 Trump arrives in Asia on Sunday, beginning his first trip to the region as president in Japan before heading to South Korea and China, then Vietnam and the Philippines. 
 
 A series of missile tests by North Korea and its sixth and largest nuclear test, defying U.N. Security Council resolutions, have fueled the most critical international challenge of Trump’s presidency. 
 
 China, under U.S. pressure to do more to rein in its ally, on Friday stressed that it had been enforcing U.N. resolutions and reiterated its opposition to the use of force. 
 
 “Over the long term, China has made unremitting efforts to appropriately resolve the peninsula nuclear issue and promote dialogue and negotiation between all parties,” Vice Foreign Minister Zheng Zeguang told reporters at a briefing in Beijing. 
 
 “You can say we’ve made our greatest effort.” 
 
 The goal of Trump’s visit will be to increase international support for efforts to deprive North Korea of resources as leverage to coerce it to give up nuclear weapons, U.S. officials said. 
 
 “The president recognizes that we’re running out of time (to deal with North Korea) and will ask all nations to do more,” White House national security adviser H.R. McMaster told reporters at a briefing in Washington. 
 
 McMaster said Trump, who has approved a variety of sanctions against North Korea while pressing China to do more, was at the beginning of his drive for Pyongyang to give up nuclear weapons. Trump has warned he would “totally destroy” North Korea if it threatened the United States. 
 
 “I think we have to be a little patient here for at least a few months to see what more we and others can do, including China,” said McMaster. “I don’t think we need to reassess our strategy now. I think we have to give it a couple of months, a few months, and then see what adjustments we might need to make.” 
 
 SHOW OF FORCE 
 
 While North Korea has not launched any missiles since Sept. 15, the longest such lull this year, a flurry of activity has been detected at its missile research facilities in Pyongyang, pointing to another possible launch, South Korea’s spy agency told lawmakers on Thursday. 
 
 Seoul held a National Security Council meeting on Friday to discuss possible unilateral sanctions against Pyongyang, and may announce the measures ahead of Trump’s arrival in South Korea, a presidential official said. 
 
 “The United States has wanted the South Korean government to take further steps to sanction the North. Unilateral sanctions by South Korea wouldn’t have much practical impact but have a symbolic importance,” the official said. 
 
 Ahead of Trump’s visit to Asia, the drills involving the U.S. bombers marked the latest show of force by the United States and its allies. 
 
 The planes flew over the Pilsung Range training area in central South Korea, Air Force spokeswoman Captain Victoria Hight said. 
 
 Japanese and South Korean fighter jets carried out sequenced missions with the U.S. bombers but no ordnance was dropped, the Air Force said. 
 
 The drill was staged at a time when three U.S. aircraft carrier groups are in the Asia-Pacific, the first time such a potent projection of force has been together in the region in a decade. 
 
 U.S. officials said earlier this week a decision may be made for the three carriers to carry out a joint exercise to coincide with Trump’s trip. 
 
 KCNA said the combination of the bomber drills with the presence of the carrier groups underscored the gravity of the situation. 
 
 “The U.S. imperialists are making last-ditch efforts to check the dynamic advance of the DPRK by deploying their nuclear strategic assets in succession, but its army and people are never frightened at such moves,” KCNA reported, referring to North Korea by the initials for its official name. 
 
 “The U.S. imperialist warmongers should not act rashly.” ||||| SEOUL/TOKYO (Reuters) - South Korean and Japanese jets joined exercises with two supersonic U.S. B-1B bombers above and near the Korean peninsula on Thursday, two days after North Korea sharply raised tension by firing a missile over Japan. 
 
 The drills, involving four U.S. stealth F-35B jets as well as South Korean and Japanese fighter jets, came at the end of annual U.S.-South Korea military exercises focused mainly on computer simulations. 
 
 “North Korea’s actions are a threat to our allies, partners and homeland, and their destabilizing actions will be met accordingly,” said General Terrence J. O’Shaughnessy, Pacific Air Forces Commander, who made an unscheduled visit to Japan. 
 
 “This complex mission clearly demonstrates our solidarity with our allies and underscores the broadening cooperation to defend against this common regional threat.” 
 
 North Korea has been working to develop a nuclear-tipped missile capable of hitting the United States and has recently threatened to land missiles near the U.S. Pacific territory of Guam. 
 
 On Monday, North Korea, which sees the exercises as preparations for invasion, raised the stakes in its stand-off with the United States and its allies by firing an intermediate-range missile over Japan. 
 
 On Thursday, its official news agency, KCNA, denounced the military drills in traditionally robust fashion, calling them “the rash act of those taken aback” by the missile test, which it described as “the first military operation in the Pacific.” 
 
 President Donald Trump, who has warned that the U.S. military is “locked and loaded” in case of North Korean provocation, reacted angrily to the latest missile test, declaring on Twitter that “talking is not the answer” to resolving the crisis over North Korea’s weapons programs. 
 
 U.S. Defense Secretary Jim Mattis was quick on Wednesday to stress that a diplomatic solution remained possible, but on Thursday he told reporters he agreed with Trump that Washington “should not be talking right now to a nation that is firing missiles over the top of Japan, an ally.” 
 
 White House spokeswoman Sarah Sanders reiterated at a regular briefing on Thursday that all options - diplomatic, economic and military - remained on the table. 
 
 Japanese Defence Minister Itsunori Onodera spoke to Mattis by telephone and agreed to keep putting pressure on North Korea in a “visible” form, Japan’s defense ministry said. Japanese Prime Shinzo Abe said he and visiting British Prime Minister Theresa May agreed to urge China, North Korea’s lone major ally, to do more to rein in North Korea. 
 
 May and Abe also discussed the possibility of adopting a new U.N. Security Council resolution on North Korea, a British government source said. 
 
 SANCTION OPTIONS 
 
 The 15-member U.N. Security Council on Tuesday condemned the firing of the missile over Japan as “outrageous” and demanded that North Korea halt its weapons programs. But the U.S.-drafted statement did not threaten new sanctions. 
 
 Two U.S. Air Force B-1B Lancer bombers fly from Andersen Air Force Base, Guam, for a mission, with an escort of a pair of Japan Self-Defense Forces F-15 fighter jets and U.S. Marines' F-35B fighter jets in the vicinity of Kyushu, Japan, in this photo released by Air Staff Office of the Defense Ministry of Japan August 31, 2017. Air Staff Office of the Defense Ministry of Japan/HANDOUT via REUTERS 
 
 Japan has been urging Washington to propose new Security Council sanctions, which diplomats said could target North Korean laborers working abroad, oil supplies and textile exports. 
 
 However, diplomats expect resistance from Russia and fellow veto-wielding power China, particularly given that new measures were only announced on Aug. 5 after North Korea tested its first two intercontinental ballistic missiles in July. 
 
 A U.S. ban on travel by Americans to North Korea comes into effect on Friday, a step announced after the death of a U.S. student shortly after his release from a 15-year prison sentence in the country, where three other Americans are still detained. 
 
 China repeated a call on Thursday for restraint by all parties. 
 
 Defence ministry spokesman Ren Guoqiang told a monthly briefing China would never allow war or chaos on the Korean peninsula, its doorstep, and military means were not an option. 
 
 “China strongly demands all sides to exercise restraint and remain calm and not do anything to worsen tensions,” Ren said, adding that Chinese forces were maintaining a normal state of alert along the North Korean border. 
 
 Chinese foreign ministry spokeswoman Hua Chunying said the situation on the peninsula was serious. 
 
 “The current tense situation on the peninsula isn’t a screenplay or a video game,” she told reporters. “It’s real, and is an immense and serious issue that directly involves the safety of people from both the north and south of the peninsula, as well as peace and stability of the entire region.” 
 
 Slideshow (12 Images) 
 
 For an interactive on North Korea's missile capabilities, click: here 
 
 For a graphic on North Korean missile trajectories, ranges, click: here 
 
 For a graphic on Kim's new act of defiance, click: here ||||| News of the US president’s possible stop off at the DMZ comes as two B-1B bombers flew over the Korean peninsula in a show of US military might 
 
 Donald Trump could soon find himself confronting North Korean soldiers on the world’s most heavily armed border, amid reports that the president is considering a visit to the demilitarised zone (DMZ) during his forthcoming trip to South Korea. 
 
 
 
 South Korea’s Yonhap news agency said the DMZ, which has separated the two Koreas since the end of their 1950-53 war, was among the candidate sites for Trump’s tour of Asia. He will also visit Japan, China, Vietnam and the Philippines. 
 
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 The report coincided with another US show of aerial strength in the region. 
 
 Two supersonic B-1B bombers flew over the Korean peninsula on Wednesday night, according to the US military. Two South Korean F-15K fighters, along with Japanese fighters, joined the drill after the bombers took off from Andersen airbase in Guam, the statement said. It was the first time Japan and South Korea had both joined US bombers on a nighttime combined exercise, it added. 
 
 The bombers carried out air-to-ground missile drills in waters off the east coast of South Korea, then repeated the drill over waters separating the South and China, the South Korean joint chiefs of staff said. 
 
 South Korea’s military described the exercise as a regular drill to bolster the country’s defences and demonstrate the strength of Seoul’s security alliance with Washington in the face of North Korean ballistic missile and nuclear tests. 
 
 US Air Force Major Patrick Applegate said: “Flying and training at night with our allies in a safe, effective manner is an important capability shared between the US, Japan and the Republic of Korea, and hones the tactical prowess of each nation’s aviators. 
 
 “This is a clear demonstration of our ability to conduct seamless operations with all of our allies anytime, anywhere.” 
 
 North Korea, however, views the drills as highly provocative, partly due to bitter memories of US bombing raids during the Korean war. 
 
 The White House sent a team of working-level officials to South Korea late last month to view possible sites for inclusion in Trump’s itinerary, Yonhap said, citing an unnamed South Korean defence source. 
 
 Trump was expected to send a strong message to North Korea, either verbally or “kinetically”, during his first trip to the peninsula as president, the source was quoted as saying. “[He] will likely do something like that and his aides are making the relevant preparations.” 
 
 If the visit goes ahead, Trump would probably spend time at the Panmunjom truce village and an observation post inside the DMZ, the source said. The White House has not commented on the reports. 
 
 The president would be following in the footsteps of Barack Obama, who peered at North Korea through binoculars during a visit to “freedom’s frontier” in 2012, and Bill Clinton, who described the 2.5-mile wide, 155-mile-long strip of land as the “scariest place on earth” when he visited in 1993. 
 
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 In April the US vice-president, Mike Pence, used an unannounced trip to the DMZ to declare that the “era of strategic patience with North Korea is over” as a North Korean soldier took his photograph from the other side of the demarcation line. 
 
 The DMZ 
 
 The land and maritime borders separating North and South Korea have been occasional flashpoints since the peninsula was split in two more than 60 years ago. 
 
 In 1976 two US army officers were hacked to death with their own axes during a confrontation with North Korean soldiers in the neutral joint security area. The area is strewn with landmines and guarded by heavily armed troops, although decades of human inactivity in the area have turned it into a notable nature reserve. 
 
 In March 2010 a North Korean torpedo sank the South Korean corvette Cheonan as it was sailing off the coast of Baengnyeong, an island just a few miles south of the border, killing 46 sailors. In November that year North Korea shelled the South Korean frontline island of Yeonpyeong, killing two soldiers and injuring civilians. 
 
 While the DMZ is a popular tourist attraction, Trump’s presence could be seen as particularly provocative by Pyongyang. 
 
 His itinerary would be likely to include a visit to the cluster of blue huts that stand directly on the military demarcation line, and where officials from North Korea and the US-led UN command have traditionally met for negotiations. 
 
 Given that the Korean war ended with an armistice and not a peace treaty, the North Korean guards and their South Korean counterparts – who are selected for their height and ability to carry off a particularly menacing taekwondo pose – are technically still at war. 
 
 Tourists are allowed to take photos of the soldiers on the other side but are instructed not to attempt to talk to them or gesture towards them. 
 
 The UN huts are unlikely to be used again anytime soon. In recent weeks Trump has dismissed the prospect of talks with North Korea. 
 
 On Monday he again tweeted his opposition to any form of engagement: “Our country has been unsuccessfully dealing with North Korea for 25 years, giving billions of dollars and getting nothing. Policy didn’t work!”
– The North Korea situation is heating up again—just in time for President Trump's visit to the region. On Thursday, two Guam-based American B-1B Lancer strategic bombers joined Japanese and South Korean jets for drills near the Korean Peninsula, Reuters reports. American authorities describe the exercises as a routine mission, but Pyongyang called it a "surprise nuclear strike drill." The move "clearly shows that the gangster-like US imperialists are the very one who is aggravating the situation of the Korean Peninsula and seeking to ignite a nuclear war," North Korea said in a statement, per NBC News. The US military says the bombers were reconfigured decades ago to carry conventional weapons, not nuclear ones. According to South Korea's spy agency, there has been "active movement of vehicles around a missile research institute in Pyongyang," suggesting more missile or nuclear tests could be imminent, CNN reports. North Korean authorities said Thursday that a report hundreds of people died in a tunnel collapse at a nuclear site was "fake news." The AP reports that later Thursday, National Security Adviser HR McMaster told reporters that North Korea will be a main focus of talks with the leaders of Japan, South Korea, China, Vietnam, and the Philippines during Trump's 12-day trip to Asia, which begins Friday. He added that the president "will use whatever language he wants to use" when discussing North Korea. (White House officials say Trump will not be visiting the DMZ.)