US Defense Secretary Jim Mattis on Thursday signed the deployment orders for additional American troops to Afghanistan, but said at the same time that he wanted to work with Pakistan to defeat terrorists, Dawn News reported.

The US defense chief also announced that American troops in Afghanistan will not only train Afghan national security forces but have also been authorised to engage the enemy.

“We intend to work with Pakistan in order to take the terrorists down. I think that’s what a responsible nation does,” said Mattis when asked at a Pentagon news briefing on Thursday “what kind of relationship the US wanted to keep with Pakistan”.

Journalists also reminded him that last week Pakistan had cancelled three high-level meetings with the US while the country’s parliament also passed a resolution describing recent US statements on Pakistan as hostile and threatening. Mattis stressed the need for continuing the relationship with Pakistan while responding to these questions, Dawn News stated.

Earlier on Thursday, the US State Department expressed a similar desire but also announced that it was placing $255 million USD of military assistance for Pakistan into an escrow account. Islamabad can only access this account if it successfully stops cross-border terrorist attacks into Afghanistan and helps the United States win the war.

Thursday’s briefing, however, focused mostly on Afghanistan as Mattis used it to announce that he has signed deployment orders to send additional troops to Afghanistan. He said he would outline the rationale for sending additional forces in more detail when he testifies to Congress on Wednesday.

Asked if he was sending combat troops or trainers, the secretary said: “Well, let me just be real clear. When you go into Afghanistan and you’re carrying a gun, you’re going into a combat zone.”

But Mattis said that most of the fight was still done by the Afghan security forces and the 38 other allies deployed in Afghanistan.

Pentagon officials told reporters on Wednesday that the military was also reorganising some of the forces already in Afghanistan to carry out the new mission, which involves engaging the enemy, Dawn News reported.

Mattis stressed that Afghan forces will remain in the lead, with the extra U.S. troops taking a support role.

"By and large this is to enable the Afghan forces to fight more effectively," Mattis said. "It's more advisers, more enablers," such as "fire support" teams, which he declined to specify but could be artillery units. He said the additional U.S. troops have not yet arrived in Afghanistan.

“I just signed the orders," Mattis said. "It's going to take a couple of days."

A Pentagon official said the United States currently had about 11,000 troops in Afghanistan to advise Afghan forces and carry out counterterrorism missions. Some media outlets reported that the Pentagon would send nearly 4,000 additional troops, some of whom might come from the 82nd Airborne Division.