Heightened tensions with North Korea have led the United States to postpone congressional testimony by the top American military commander in South Korea and delay an intercontinental ballistic missile test from a West Coast base.
North Korea, after weeks of war threats and other efforts to punish South Korea and the US for joint military drills, has told other nations that it will be unable to guarantee diplomats' safety in the North's capital from Wednesday.
US General James Thurman, the commander of the 28,000 American troops in South Korea, will stay in Seoul as "a prudent measure" rather than travel to Washington to appear this coming week before congressional committees, Army Colonel Amy Hannah said in an email.
Col Thurman has asked the Senate Armed Services Committee, the House Armed Services Committee and the House Appropriations subcommittee on defence to excuse his absence until he can testify at a later date.
The top US military officer, General Martin Dempsey, who just wrapped up a visit to Afghanistan, said he had consulted with Col Thurman about the rising tensions on the Korean peninsula.
Gen Dempsey said the US has been preparing for further provocations or action, "considering the risk that they may choose to do something" on one of two nationally important anniversaries in April - the birth of North Korean founder Kim Il Sung and the creation of the North Korean army.
Gen Dempsey said both Col Thurman and South Korea's Joint Chiefs of Staff chairman, General Jung Seung-jo, decided it would be best for them to remain in Seoul rather than come to Washington. The Korean general had planned to meet with Gen Dempsey, the US Joint Chiefs of Staff chairman, in mid-April for regular talks.
Gen Dempsey said that instead of meeting in person with Col Thurman and Gen Jung in Washington, they will consult together by video-teleconference. Asked whether he foresees North Korea taking military action soon, Gen Dempsey said: "No, but I can't take the chance that it won't".
The Pentagon has also postponed an intercontinental ballistic missile test that was set for the coming week at Vandenberg Air Force Base in California, a senior defence official said.
The official said US Defence Secretary Chuck Hagel decided to put off the long-planned Minuteman 3 test because of concerns the launch could be misinterpreted and exacerbate the Korean crisis. Mr Hagel made the decision on Friday, the official said.