BAGHDAD — U.S. Defense Secretary Jim Mattis said today the United States does not intend to seize Iraqi oil, shifting away from an idea proposed by President Donald Trump that has rattled Iraq’s leaders.

Mattis’ arrived on an unannounced visit in Iraq as the battle to oust Islamic State militants from western Mosul moved into its second day, and as the Pentagon considers ways to accelerate the campaign against IS in Iraq and Syria.

Those efforts could be complicated by Trump’s oil threat and his inclusion of Iraq in the administration’s travel ban — twin blows that have roiled the nation and spurred local lawmakers to pressure Prime Minister Haider al-Abadi to reduce cooperation with Washington.

“I think all of us here in this room, all of us in America have generally paid for our gas and oil all along, and I’m sure that we will continue to do that in the future,” Mattis told reporters traveling with him. “We’re not in Iraq to seize anybody’s oil.”

His comments may provide some reassurance to the Iraqis. But the tensions come at a critical point in the war against IS, with two key battles in the works: the fight to take control of west Mosul, and the start of a campaign in Syria to oust IS from Raqqa, the capital of its self-declared caliphate.