WASHINGTON (Reuters) - U.S. Defense Secretary Jim Mattis said on Friday that he expected to see a larger U.S. civilian presence in Syria, including contractors and diplomats, as the fight against Islamic State militants nears its end and the focus turns toward rebuilding and ensuring the militants do not return.

FILE PHOTO: U.S. Defense Secretary Jim Mattis addresses a news conference during a NATO defence ministers meeting at the Alliance headquarters in Brussels, Belgium, February 16, 2017. REUTERS/Francois Lenoir/Files

The United States has about 2,000 troops in Syria fighting Islamic State. Mattis’ comments are likely to anger Syrian President Bashar al-Assad, who has previously called U.S. troops “illegal invader” forces.

“What we will be doing is shifting from what I would call an offensive, shifting from an offensive terrain-seizing approach to a stabilizing ... you’ll see more U.S. diplomats on the ground,” Mattis told reporters.

He has previously stated that U.S. forces will stay in Syria as long as Islamic State fighters want to fight and prevent the return of an “ISIS 2.0,” using an acronym for Islamic State.

His comments marked the first time Mattis has indicated there would be an increase of civilians in parts of the country retaken from Islamic State militants.

“Well, when you bring in more diplomats, they are working that initial restoration of services, they bring in the contractors, that sort of thing,” he said.

“There is international money that has got to be administered, so it actually does something, it doesn’t go into the wrong people’s pockets,” he added.

The contractors and diplomats would also face the task of training local forces to clear improvised explosive devices (IEDs) and helping ensure that Islamic State does not retake territory.

“It is an attempt to move towards the normalcy and that takes a lot of support,” said Mattis. It was not clear how many U.S. diplomats would serve in Syria or when. The United States has suspended diplomatic relations with Syria due to the civil war.

Assad’s forces, helped by Russian air power and Iran-backed militias, have managed to re-establish control over most of Syria over the past two years.

The U.S.-led coalition battling Islamic State in Syria has repeatedly said it does not seek to fight Assad’s forces, though Washington wants the president to step down.

When asked whether Syrian government forces could move to disrupt the U.S. plans, Mattis said: “That would probably be a mistake.”

Separately, in a letter to members of the U.S.-led coalition fighting Islamic State, a senior U.S. official said he expected military operations to continue over the first quarter of 2018.

“The United States is prepared to remain in Syria until we are certain that ISIS is defeated, stabilization efforts can be sustained, and there is meaningful progress in the Geneva-based political process,” said Brett McGurk, U.S. special envoy to the coalition.