PRESIDENT Donald Trump praised Japan as a “crucial ally” and warned adversaries not to test America’s resolve as he kicked off his first trip to Asia.

Trump landed at Yokota Air Base outside Tokyo and was greeted by cheering service members.

He then donned a bomber jacket for a speech in which he touted American firepower and the US alliance with Japan.

“Japan is a treasured partner and crucial ally of the United States and today we thank them for welcoming us and for decades of wonderful friendship between our two nations,” he said, speaking in front of an American flag inside an airplane hangar.

Trump was expected to spend much of his 12-day, five-country Asian tour exhorting allies and rivals to step up efforts to counter the dangers posed by North Korea, which continues to move forward with its nuclear weapons program.

Both he and North Korean leader Kim Jong Un have been engaged in an escalating war of words, with Trump repeatedly referring to the North Korean leader as “Little Rocket Man” and threatening in a recent speech to “totally destroy” the nation if necessary.

Even before he landed, Trump used the first moments of the trip to denounce the North as “a big problem” that must “be solved.”

“There’s been 25 years of total weakness, so we are taking a very much different approach” towards the North, he said.