Seoul (Reuters): President Donald Trump flew into South Korea and met with US troops stationed there on Tuesday, the closest he has come to the frontlines of the nuclear standoff with North Korea, on a visit that could further aggravate tensions with Pyongyang.

Landing at Osan Air Base outside Seoul, the president and First Lady Melania Trump stepped down from Air Force One onto a red carpet as he began his 24-hour visit with a military honor guard and 21-gun salute.

He then flew by helicopter to Camp Humphreys, the largest U.S. military installation in the country.

The White House says Trump’s trip is intended to demonstrate U.S. resolve over his hardline approach to the North Korean nuclear and missile threats, but many in the region fear further bellicose presidential rhetoric could increase the potential for a devastating military conflict on the Korean peninsula.

Three US aircraft carrier strike groups will exercise together in the Western Pacific in the coming days in a show of force rarely seen in the region, US officials said, as Trump continues his Asia tour aimed at warning North Korea and forging a united front against it and developing trade.

Pyongyang’s recent nuclear and missile tests in defiance of UN resolutions and an exchange of bellicose insults between Trump and North Korean leader Kim Jong Un have raised the stakes in the most critical international challenge of Trump’s presidency.

On the second leg of his five-nation trip, Trump toured the sprawling Camp Humphreys garrison, which lies about 100 km (60 miles) from the border with reclusive North Korea.