Vice President Mike Pence lays a wreath at the Seoul National Cemetery in Seoul, South Korea. Pence, on an Asia trip, will try to reassure South Korea and Japan that the U.S. will defend them against North Korea.

Lee jin-man / The Associated Press

As President Trump asserted on Sunday that China was working with the United States on “the North Korea problem,” his vice president visited a military base near the Demilitarized Zone separating the Koreas, a day after the North conducted a failed missile launch.

Vice President Mike Pence, who has called the failed missile launch “a provocation,” arrived at Camp Bonifas on Monday morning for a briefing with military leaders and to meet with American troops stationed there.

Pence warned in a visit to the DMZ dividing North and South Korea that the North Korean people and military “should not mistake the resolve of the United States of America to stand with our allies.” He said the “era of strategic patience is over” with North Korea.

Pence told reporters near the DMZ that the alliance between South Korea and the U.S. is “iron-clad” and is reiterating that “all options are on the table” to pressure North Korea to get rid of its nuclear weapons and missile program.

While the North did not conduct a nuclear test, the specter of a potentially escalated U.S. response trailed Pence as he began a 10-day trip to Asia amid increasing tensions and heated rhetoric.

Trump’s national security adviser cited Trump’s recent decision to order missile strikes in Syria after a chemical attack blamed on the Assad government as a sign that the president “is clearly comfortable making tough decisions.”

But at the same time, H.R. McMaster said, “it’s time for us to undertake all actions we can, short of a military option, to try to resolve this peacefully.”

In a broadcast interview that aired on Sunday, McMaster said the U.S. would rely on its allies as well as on Chinese leadership to resolve the issues with North Korea.

“I mean, North Korea is very vulnerable to pressure from the Chinese,” McMaster said on ABC’s “This Week.”

The bottom line, McMaster said, is to stop the North’s weapons development and make the Korean Peninsula nuclear-free: “It’s clear that the president is determined not to allow this kind of capability to threaten the United States. And our president will take action that is in the best interest of the American people.”

After a two-month policy review, officials settled on a policy dubbed “maximum pressure and engagement,” U.S. officials said Friday. The administration’s immediate emphasis, the officials said, will be on increasing pressure on Pyongyang with the help of Beijing.

The officials weren’t authorized to speak publicly and requested anonymity.

Pence will be tasked with explaining the policy in meetings with leaders in South Korea and Japan during the trip, which will also include stops in Indonesia and Australia. He will aim to reassure allies in South Korea and Japan that the U.S. will take appropriate steps to defend them against North Korean aggression.

A North Korean missile exploded during launch on Sunday, U.S. and South Korean officials said. The high-profile failure came as the North tried to showcase its nuclear and missile capabilities around the birth anniversary of the North’s late founder and as a U.S. aircraft carrier neared the Korean Peninsula.

A White House foreign policy adviser traveling with Pence said no U.S. response to the missile launch was expected because there was no need for the U.S. to reinforce the failure.