Mike Pence warned North Korea the "era of strategic patience is over" as he visited the Korean Demilitarised Zone within 24 hours of Pyongyang's failed missile test.
The US vice president said Washington and its allies will achieve its objectives through "peaceable means or ultimately by whatever means are necessary" to protect South Korea and stabilise the region.
He said President Donald Trump is hopeful that China will use its "extraordinary levers" to pressure the North to abandon its weapons.
Mr Pence, who had previously called the failed missile launch "a provocation," arrived at Camp Bonifas on Monday morning for a briefing with military leaders and to meet American troops stationed there.
The joint US-South Korean military camp is just outside the 2.5-mile-wide DMZ.
He later stood a few yards from the military demarcation line outside Freedom House, gazing at two North Korean soldiers across the border and then a deforested stretch of North Korea from a lookout post in the hillside.
Mr Pence said there had been a period of patience in the 25 years since North Korea first obtained nuclear weapons.
"But the era of strategic patience is over," he said.
"President Trump has made it clear that the patience of the United States and our allies in this region has run out and we want to see change.
"We want to see North Korea abandon its reckless path of the development of nuclear weapons, and also its continual use and testing of ballistic missiles is unacceptable."
Mr Pence's visit, full of Cold War symbolism, comes amid increasing tensions and heated rhetoric on the Korean Peninsula.
While the North did not conduct a nuclear test, the spectre of a potential escalated US response accompanied Mr Pence as he began a 10-day trip to Asia.
The US n ational security adviser cited Mr 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, HR 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 TV interview that aired on Sunday, Mr McMaster said the US would rely on its allies as well as on the Chinese leadership to resolve the issues with North Korea.
He said t he US is focussed on stopping the North's weapons development and making 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."
Mr Pence will be tasked with explaining US 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 US will take appropriate steps to defend them against North Korean aggression.
A North Korean missile exploded during launch on Sunday, US 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 US aircraft carrier neared the Korean Peninsula.
Mr Trump, spending the Easter weekend at his Florida resort, reinforced his commitment to the armed forces under his control.
"Our military is building and is rapidly becoming stronger than ever before," he tweeted.
More directly on North Korea, the president returned to a theme of placing much emphasis on China for reining in the North.
Last week, he said he would not declare China a currency manipulator, pulling back from a campaign promise, as he looks for help from Beijing, which is the North's dominant trade partner.
On Sunday he tweeted: "Why would I call China a currency manipulator when they are working with us on the North Korean problem? We will see what happens!"
