Pence took off for Tokyo from a USA air base south of Seoul, where he assured leaders of the "iron-clad" alliance with the United States.
The Latest on U.S. Vice President Mike Pence's trip to Asia (all times local): 12:15 p.m. U.S. Vice President Mike Pence has arrived in Japan for the second stop of a 10-day Asia tour.
Pence told business leaders before leaving Seoul that the Trump.
White House spokesman Sean Spicer said Trump would not be "drawing red lines in the sand" with North Korea.
He also said, "We are with you 100 percent", adding that the USA always seeks peace. "I think that the action that he took in Syria shows that when appropriate, this president will take decisive action".
Such belligerent rhetoric from North Korea's state media and officials is common.
The Trump administration has said military action remains an option for dealing with North Korea.
North Korea has conducted a series of missile launches and nuclear tests in defiance of United Nations sanctions, including a failed missile launch on Sunday.
Mr Pence had flown in from South Korea where he had visited the demilitarized zone dividing it from North Korea.
The BBC's Stephen Evans in Seoul says USA policy now seems to be to persuade China to contain North Korea while keeping the economic and military pressure on. But the vice president expressed impatience with the unwillingness of the North to move toward ridding itself of nuclear weapons and ballistic missiles.
KUHN: Well, at his summit meeting with President Trump this month in Mar-a-Lago, Fla., President Xi Jinping did promise to coordinate and communicate with the USA on the North Korean issue.
The North casts the U.S. as the aggressor.
What does North Korea say?
China still has a lot it could do, things that are even more damaging like cutting all oil exports to North Korea.
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"We're going to be watching what the Chinese do", she said.
Russia's Foreign Minister Sergei Lavrov said Moscow would not tolerate "missile adventures by Pyongyang" but a unilateral use of power by the United States would be "a very risky course".
Advocates for the TPP, negotiated by former President Barack Obama, said it would have dramatically reduced tariffs on US goods and opened new markets. "Trump is more impulsive and unpredictable than Kim Jong Un", he told viewers of his Sunday prime-time Vesti Nedelyi program, which earlier this year praised Trump for his pledge of warmer relations with Russian Federation.
For its part, China made a plea for a return to negotiations. Foreign Ministry spokesman Lu Kang said tensions need to be eased on the Korean Peninsula to bring the escalating dispute there to a peaceful resolution. Lu said Beijing wants to resume the multi-party negotiations that ended in stalemate in 2009 and suggested that US plans to deploy a missile defense system in South Korea were damaging its relations with China. "But dialogue for the sake of having dialogue is meaningless".
He told the parliamentary session that the government is formulating measures including protecting foreigners, creating landing procedures, building and operating shelters, and screening asylum seekers.
North Korea's deputy United Nations ambassador on Monday accused the USA of turning the Korean Peninsula into "the world's biggest hot spot" and creating "a unsafe situation in which a thermonuclear war may break out at any moment".
"If the U.S. is reckless enough to use military means it would mean from that very day, an all out war".
Pence said on Monday the world had seen Trump's resolve in the past two weeks, with a US missile attack on a Syrian airfield and the dropping of a powerful non-nuclear bomb on Islamic State fighters in Afghanistan. They are expected to be joined by U.S. Commerce Secretary Wilbur Ross, in Tokyo for his own talks with Japanese Trade Minister Hiroshige Seko.
Kim called the news conference to "categorically reject" the USA decision to hold an open meeting of the U.N. Security Council on April 28.
Defying worldwide pressure, the North on Sunday test-fired another missile and fears are growing it may also be preparing a sixth nuclear test. One called for "dual-track" talks on denuclearizing the Korean Peninsula and replacing the armistice that ended the 1950-53 Korean War with a formal peace treaty.
"North Korea would do well not to test his resolve or the strength of the armed forces of the United States in this region", Pence said.
There, he bluntly warned North Korean leader Kim Jong-un that "the era of strategic patience is over".
In Beijing, Chinese Foreign Minister Wang Yi today made a new appeal for calm on the Korean Peninsula.