A top White House foreign policy advisor on Sunday became the latest Trump official to warn that while diplomatic pressure was preferable, U.S. military action is very much on the table.
On Saturday, the North held a large military parade to mark the anniversary of the country's late founder, Kim Il Sung.
North Korea launched a long-range rocket and conducted two nuclear tests previous year, including its most powerful to date.
A White House foreign policy adviser traveling with Pence said no US response to the missile launch was expected because there was no need for the U.S.to reinforce the failure.
"Our commitment to this historic alliance with the courageous people of South Korea has never been stronger".
Meanwhile, US Defence Secretary Jim Mattis said that President Donald Trump and his military team are aware of the missile launch.
After a day that only furthered the growing tension over North Korea - and the tumult of finding out about the missile launch en route - Pence's presence here on the ground in Seoul seemed to take on a stronger significance.
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Pence said Monday Trump was "very hopeful that China will take actions to bring about a change of policy in North Korea". The vice president spoke at a dinner after attending Easter church services with service members at the garrison.
"Unfortunately the President's failure to name China a currency manipulator is symptomatic of a lack of real, tough action on trade against China", Senate minority leader Chuck Schumer said.
South Korea, which hosts 28,500 US troops and holds a presidential election on May 9, warned of punitive action if the Sunday launch led to further provocation.
Physicist and North Korea nuclear watcher David Albright, of the Institute for Science and International Security, estimated in a report last week provided to The Associated Press that through 2020, North Korea will have enough plutonium and weapon-grade uranium for about 25-50 nuclear weapons.
That is why what happens on the Korean Peninsula has an effect in the Middle East. Iran is already believed to have acquired missile technology from North Korea.
Pence flew to South Korea on the first stop of a four-nation Asia tour meant to show America's allies - and remind its adversaries - that the Trump administration is not turning its back on the increasingly volatile region. A USA aircraft carrier, the USS Carl Vinson, is heading to waters off Korea in a show of force.
Trump's decision to order a cruise missile strike on a Syrian airfield this month, in response to what he said was Syria's use of chemical weapons, raised questions about his plans for reclusive North Korea.
McMaster said the launch "fits a pattern of provocative and destabilising and threatening behaviour on the part of the North Korean regime".
US working on "range of options" against N Korea: McMaster
Pacific Command says in an emailed statement. "Trump is always making provocations with his aggressive words", Han Song Ryol said. For example, five years ago North Korea held a parade in which it pretended to display intercontinental ballistic missiles.
China is North Korea's only major ally.
Last August a submarine-launched ballistic missile tested from Sinpo flew 500 kilometers (300 miles) towards Japan. That launch came shortly before Trump's first meeting with Chinese leader Xi Jinping.
CNN's Will Ripley in Pyongyang, North Korea, reported there was no immediate confirmation from North Korean state media about the launch.
His remarks at the service came after North Korea launched a missile off its east coast. His visit comes just after a failed missile launch by the North.
While interest in North Korea spikes immediately after a missile launch, within hours internet search traffic is again dominated by TV comedy shows, taxes and real estate.
Six-nation negotiations on dismantling North Korea's nuclear program in exchange for aid fell apart in early 2009.
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The oath was administered during the White House ceremony by Justice Anthony Kennedy, whom Gorsuch once served as a law clerk. A new study , conducted by Northwestern's Pritzker School of Law, looked at oral arguments for the years 1990, 2002 and 2015.