The US commander in South Korea, General James Thurman, has cancelled a scheduled trip to Washington this week due to tensions with North Korea, a spokeswoman said on Sunday.
Thurman had been due to testify before three congressional committees, where he was expected to discuss the US response to threats from Pyongyang.
The North’s provocations prompted a thinly veiled rebuke from China over the weekend.
“Given the current situation, General Thurman will remain in Seoul next week as a prudent measure,” said Colonel Amy Hannah, a spokeswoman for US forces in South Korea, in an email message.
The move is the latest demonstration of US caution and concern after more than a month of North Korean rhetoric that has included threats to launch a nuclear attack on the United States and to wage war with Seoul.
The United States has already revamped its missile defence plans for Alaska and is deploying a missile defence system to Guam, a US territory in the Pacific.
On Saturday, a US defence official said Washington had also decided to delay a long-planned missile test scheduled for next week out of California “to avoid any misperception or miscalculation”, given tensions with Pyongyang.
Thurman had been due to testify before the Senate Armed Services Committee, the House Armed Services Committee and a panel of the House Appropriations Committee.
Thurman asked the committees to excuse his absence until he can testify at a later date, Hannah said.
“He looks forward to appearing before the committee at the earliest possible date,” she said.
Despite its bellicose rhetoric, Pyongyang has not taken any military action and has shown no sign of preparing its 1.2 million-strong army for war, indicating the threats are partly intended for domestic consumption to bolster young leader Kim Jong-un.
South Korean media said on Friday that the North had moved two medium-range missiles to its east coast but there has been no confirmation of such a move. Washington has said it would not be surprised if the North conducted another missile test.
North Korean authorities have told diplomatic missions in Pyongyang they could not guarantee their safety from Wednesday, after saying conflict was inevitable amid joint US-South Korean military exercises due to last until the end of the month.
Staff at embassies appeared to be remaining in place over the weekend.