The Trump administration has signalled a more forceful United States stance toward North Korea's recent missile tests and threats, including a warning from Trump that North Korean leader Kim Jong Un has "gotta behave".
Since taking office, however, USA tensions with North Korea have soared amid a drumbeat of missile tests and fears Pyongyang may be readying a sixth nuclear test.
"We appreciate the challenging times in which the people of Japan live with increasing provocations from across the Sea of Japan", he after arriving in Japan with his wife and two daughters earlier in the day.
United States vice-president Mike Pence said his administration would not relent until it achieves its objective of ensuring the Korean Peninsula is free of nuclear weapons.
"We need to apply pressure on North Korea so they seriously respond to a dialogue" with the global community, he said, urging China and Russian Federation to play more constructive roles on the issue.
Mr Pence's comments, delivered in Japan, came a day after he spoke in South Korea where he said the "the era of strategic patience is over", a comment that was widely seen as hinting at U.S. military action.
The United States is aware of a higher-than-usual level of activity by Chinese bomber planes, signaling a possible heightened state of readiness, USA officials told Reuters on Thursday, but downplayed concerns and left open a range of possible reasons.
"That creates a framework within which countries can better assess whether the deal itself is what we call win-win arrangement", he said.
This article is based on a larger analysis of the prospects of nuclear fallout with North Korea published April 14.
The North regularly launches short-range missiles, but is also developing mid-range and long-range missiles meant to target US troops in Asia and, eventually, the USA mainland.
"President Trump is very hopeful that the Chinese will undertake to use the considerable leverage that they have over the economic lifeblood of the North Korean economy", she said.
A sales manager for a Sinotruck dealer, Zhongnanhai, said the company exports about 1,000 trucks to North Korea every year under contracts that specify the vehicles are designed and manufactured for civilian use.
North Korea could react to a potential U.S. strike by targeting South Korea or Japan, and officials in both countries have been ill at ease with the more bellicose language deployed by President Donald Trump's administration.
Trump also said he is working with China "with great respect" and he has "great respect" for Xi, but it remains to be seen what he can do. He said the American commitment to South Korea is "iron-clad and immutable". Yet the vice president suggested that the message being delivered from the White House was getting through.
"If the U.S.is planning a military attack against us, we will react with a nuclear pre-emptive strike by our own style and method", Han said.
"Japan and the United States can play a pivotal role in spreading high-level fair [trade] rules over Asia and the Pacific region", he said.
If the United States and the two Koreas "let war break out, they must shoulder that historic culpability and pay the corresponding price", said Chinese Foreign Minister Wang Yi.
The United States was the most important participant, he said.
Pence's economic discussions in Tokyo will be closely watched to see how hard a line Washington is prepared to take on trade.
Trump has ordered a wide-ranging review of America's deficits with top trading partners aimed at determining how much is the result of cheating, unfair practices and currency manipulation.
"If North Korea responds to military threats with further missile or nuclear tests, or a limited conventional strike against South Korea, President Trump may be forced to back up his strong words with military action or appear a paper tiger".