NurPhoto via Getty Images

WASHINGTON (Reuters) - U.S. Defense Secretary Jim Mattis said on Thursday he had signed deployment orders to send additional troops to Afghanistan but did not specify the size of the force.

“Yes, I have signed orders but it is not complete. In other words I have signed some of the (orders for) troops that will go and we are identifying the specific ones,” Mattis told reporters.

Mattis declined to comment on how many additional troops were included in the orders, but U.S. officials have told Reuters that President Donald Trump has given Mattis the authority to send about 4,000 additional troops to Afghanistan.

“It is more advisers, it is more enablers, fire support, for example,” Mattis said. He added that no additional troops had moved in yet and could take a “couple of days.”

After a months-long review of his Afghanistan policy, Trump committed the United States last week to an open-ended conflict in the country and promised a stepped-up campaign against Afghan Taliban insurgents.

The security situation in Afghanistan has deteriorated for the United States and Afghan government over the past few years.

The Afghan government was assessed by the U.S. military to control or influence almost 60 percent of Afghanistan’s 407 districts as of Feb. 20, a nearly 11 percentage-point decrease from the same time in 2016, according to data released by the U.S. Special Inspector General for Afghanistan Reconstruction.

About 11,000 U.S. troops are serving in Afghanistan, the Pentagon said on Wednesday, thousands more than it has previously stated.