Updated

The Trump administration on Monday opened the door to cooperating with Russia "or anyone else" to combat the Islamic State group in Syria, suggesting it could reverse a previous refusal to coordinate military action with Moscow as long as it backs the Syrian government.

"I think if there's a way that we can combat ISIS with any country, whether it's Russia or anyone else, and we have a shared national interest in that, sure, we'll take it," White House press secretary Sean Spicer said.

Asked if the openness extended to working with Syrian President Bashar Assad, who has been condemned internationally for killing civilians, Spicer said, "We're not going to get together with people under the guise of defeating ISIS if that's not truly their guise." He added, "So let's not take that too far."

Spicer also suggested that Trump already has told Defense Secretary James Mattis to change the U.S. approach to fighting the Islamic State.

"I think he has ordered it," Spicer said, adding that Trump would discuss the matter with Mattis during a visit to the Pentagon Friday.

"At that time, he will continue to have conversations about what he wants from them and the joint chiefs," he added, referring to the military service chiefs.

During the more than two years that President Barack Obama directed U.S. military action against IS in Syria, he resisted Russian overtures to coordinate military action. Obama believed Moscow was acting counter to U.S. interests by propping up Assad, whose government Obama called illegitimate. The Pentagon has maintained a hotline with the Russian military to deal with the narrower issue of avoiding air accidents in Syria.

With Trump in the White House, Moscow seems eager to draw the new administration into closer military cooperation, perhaps reflecting Trump's frequent statements during the presidential campaign that he welcomed opportunities to improve relations with Moscow.

On Monday, the Russian Ministry of Defense announced that the U.S. had provided targeting information for a joint airstrike against Islamic State fighters in Syria. But Pentagon officials flatly denied the Russian assertion.

U.S. Air Force Col. John Dorrian, chief spokesman for the U.S.-led coalition in Baghdad, called the Russian statement "rubbish." At the Pentagon, a spokesman, Maj. Adrian J. Rankine-Galloway, said the U.S. military is not providing targeting information to the Russians or coordinating air operations with them.

Trump has not yet spelled out how he will change the U.S. approach in Syria or Iraq. During the campaign he said that as president he would ensure the Islamic State's quick defeat. At CIA headquarters over the weekend, he repeated his campaign assertion that the U.S. had erred in not taking control of Iraq's oil as compensation for having ousted President Saddam Hussein in 2003.

"If we kept the oil you probably wouldn't have ISIS because that's where they made their money in the first place," Trump said. "So we should have kept the oil. But, OK, maybe you'll have another chance."

Asked what Trump meant, Spicer said, "We want to be sure our interests are protected. We're going into a country for a cause. He wants to be sure America is getting something out of it for the commitment and sacrifice it is making."