U.S. Secretary of Defense Robert Gates says North Korea's recent provocations, including nuclear and missile tests, have not reached a level that would warrant additional U.S. troops in the region.

Flying to Singapore for a security conference, he told reporters aboard his military jet that no one in the Obama administration sees this as a crisis situation.

He said that the latest developments, though provocative and accompanied by aggressive rhetoric, are disturbing and will require a multilateral, diplomatic effort in order to be resolved.

He expressed strong concern on North Korean exports of missile and nuclear technologies and stressed cooperation, particularly with Russia and China, in efforts to curb them.

While in Singapore, Gates will meet with defense ministers of South Korea, Japan and China as part of a regional security conference.