BALAD, Iraq — Defense Secretary Robert Gates urged Middle East nations to support the fight against terror Saturday, then traveled to Iraq to meet with commanders as the U.S. prepares to cut its troop levels and begin to pull forces out of the cities.

The unannounced visit to Iraq on Saturday comes as President-elect Barack Obama prepares to take office and begin to implement what many expect will be an accelerated withdrawal of troops. During Obama's presidential campaign, he said he wanted combat troops out of Iraq in 16 months, but he has also said he would listen to the advice of his commanders on the ground.

A security agreement between the U.S. and Iraq mandates that combat forces leave the cities by next June, and leave Iraq in three years.

Earlier in Bahrain, Gates urged Middle East nations to help fight the spread of violent extremism by funding and training Afghan security forces and reaching out more aggressively to the fledgling government in Iraq.

Gates also assured the gathering of Persian Gulf leaders in Bahrain that Obama will continue the U.S. commitment to the Middle East, including efforts to fight terrorism and develop a two-state solution between Israel and the Palestinians.

And as the lone Republican holdover from the Bush Cabinet to the Obama team, Gates issued a public warning that any effort by terrorists to test the new administration would be a mistake because there has been extensive planning to ensure a smooth transition.

"Anyone who thought that the upcoming months might present opportunities to 'test' the new administration would be sorely mistaken," Gates said. "President Obama and his national security team, myself included, will be ready to defend the interests of the United States and our friends and allies from the moment he takes office on Jan. 20."