The United States is ready to change fundamentally its military presence on the Korean Peninsula (search) and in Europe, where static U.S. defenses have stood guard for decades, Defense Secretary Donald H. Rumsfeld (search) said Thursday.

"It's time to adjust those locations from static defense to a more agile and a more capable and a more 21st century posture," Rumsfeld told reporters flying with him to this Asian city-state.

While declining to discuss specifics, Rumsfeld's remarks were a clear indication that after months of internal Pentagon calculations about how best to array American forces abroad, and after a period of consultations with U.S. European and Asia allies, the first major changes are about to be happen.

Rumsfeld did not mention perhaps the most immediate change: the move of a 2nd Infantry division brigade this summer to Iraq from its traditional posts in South Korea. The Pentagon has not said whether that unit would return to South Korea after its Iraq duty, but that appears unlikely.

Responding to concerns expressed by some in Asia that removing 3,600 U.S. troops from Korea for use in Iraq -- and possibly several thousand more at a later time -- would be seen by communist North Korea as a sign of American weakness, Rumsfeld said such an interpretation would be mistaken.

"This country will not weaken the deterrent or the defense capabilities that we have, even though numbers and locations may shift and evolve as technologies evolve and as circumstances change," said Rumsfeld, holding an on-board news conference on his E4-B modified 747 jet which serves as a flying national command post equipped for use in wartime.

"We have been for a long time, in effect, where we were when the Cold War ended," he said.

There are about 37,000 U.S. troops in South Korea, about 47,000 in Japan and about 100,000 in Europe.

Rumsfeld flew 22 hours nonstop from Washington to Singapore to attend an international security conference called the Shangri-La Dialogue, where he is scheduled to deliver a speech on U.S. security policy on Asia and the Pacific on Saturday.

He said he also planned to meet separately with his counterparts from Japan, South Korea, Australia and Singapore, in addition to visiting U.S. sailors and Marines aboard the USS Essex, a helicopter carrier that is in port at Singapore.

Rumsfeld said he would fly to Bangladesh later Saturday for talks with government officials about their military's possible interest in peacekeeping operations either in Iraq or Afghanistan. He said he did not intend to formally request that they send troops to either country.