US Defence Secretary Robert Gates has warned opponents of the United States against trying to "test" Barack Obama with a crisis in the early days of his presidency.
Mr Gates, who is staying in his post, said the new president's security team is ready to defend US national interests from the moment he takes office on 20 January.
At a regional security forum in Bahrain, Mr Gates said Middle East and Gulf security would remain a key issue for the US.
On Iran, Mr Gates denied that the United States was seeking regime change, but wanted to see "a change in policies and a change in behaviour".
The former CIA director who became defence secretary in 2006, also repeated calls for Sunni Arab countries to back Iraq with full diplomatic ties.
Mr Obama's running mate, Senator Joe Biden, warned during the election campaign that there would be an attempt to test Mr Obama's mettle with an early international crisis.
Mr Gates visited Afghanistan on Thursday and promised more troops and resources as the US reduces its presence in Iraq.