Defense Secretary Robert M. Gates warned Saturday that foreign powers should not try to “test” President-elect Barack Obama with a crisis in his first months in office and that Mr. Obama remained committed to the security of the Persian Gulf and American interests in the region.

Mr. Gates, speaking at a conference on regional security here, said that Mr. Obama and his advisers had done more extensive planning across the government for the transition than at any time he could remember and asserted that they would therefore be prepared from day one. Mr. Gates, who is staying on as Defense secretary, has worked for seven presidents. Mr. Obama will be his eighth.