Vice President Mike Pence Monday warned North Korea not to test Washington's patience after holding talks with acting South Korean leader Hwang Kyo-ahn in Seoul.
Pence arrived a day earlier amid expectations among officials in the South that Pyongyang could conduct a sixth ever nuclear test any time.
"The era of strategic patience is over," he told a joint news conference while referring to former President Barack Obama's Pyongyang policy.
Citing U.S. leader Donald Trump's decision to carry out recent military strikes in Syria and Afghanistan, Pence said: "North Korea will do well not to test his (Trump's) resolve or strength of the armed forces of the United States in this region."
Pence is the most senior member of the Trump administration to visit South Korea to date.
Following a trip to the heavily guarded inter-Korean border earlier in the day, the vice president vowed the allies would defeat any North Korean attack through "an overwhelming and effective response."
He insisted "all options are on the table," as speculation intensifies over a possible pre-emptive American strike on the North in the wake of Washington's decision to dispatch a nuclear-powered aircraft carrier group to the peninsula.
The American official will head to Japan on Tuesday, the second stop on a four-nation tour.
