WASHINGTON >> Defense Secretary Jim Mattis said today that he had signed deployment orders for some of the U.S. reinforcements that are to be sent to Afghanistan.

It is the first tangible step that the Pentagon has taken to carry out the new strategy that President Donald Trump announced last week to step up the fight in Afghanistan and try to take back the initiative from the Taliban.

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

Although Mattis did not say which forces were being deployed, administration officials have previously said the Pentagon will send nearly 4,000 additional troops, some of whom are expected to come from the 82nd Airborne Division.

The United States has about 11,000 troops in Afghanistan to advise Afghan forces and carry out counterterrorism missions.

The new reinforcements, officials have said, will enable the United States to advise select Afghan brigades in the field, step up the effort to train Afghanistan’s special operations forces and call in U.S. and allied air and artillery strikes.

“When you go into Afghanistan and you are carrying a gun, you are going into a combat zone,” Mattis said. “By and large, this is to enable the Afghan force to fight more effectively. It is more advisers. It is more enablers — fire support, for example.”

The military is also reorganizing some of the forces already in Afghanistan to carry out the new mission.

Pentagon officials have yet to publicly explain the new mission in detail or make the case why they think the new strategy will be effective when the deployment of 100,000 troops to Afghanistan during the Obama administration failed to break the back of the Taliban and other extremist groups, or force them to the negotiating table.

Mattis said he would begin to outline the rationale for the forces in more detail when he testifies to Congress on Sept. 6.