The U.S. military’s top officer, Chairman of the Joint Chiefs of Staff Gen. Joseph F. Dunford, Jr., arrived in Afghanistan Monday to finalize plans for adding several thousand more troops there.

Two weeks ago, Defense Secretary Jim Mattis told Congress he will present a new plan for Afghanistan and the region in mid-July.

“We are not winning in Afghanistan right now, and we will correct this as soon as possible,” said Mattis, who called the new plan a “fundamental change” from the Obama administration’s policy.

Mattis told lawmakers part of the change involves moving U.S. troops closer to the fight to help Afghan forces -- decimated with record casualties last year -- to call in airstrikes against the Taliban. In this way, officials say the new strategy in Afghanistan will look like the current fight against ISIS in Iraq and Syria, with more American troops calling in airstrikes to support local forces.

Earlier this month, President Trump gave his defense secretary the authority to determine how many more troops were needed in Afghanistan.

Defense officials say Mattis’s authority from the president to increase troops is in the 3,000-5,000 range and not above that number. While not a blank check, the move would enable Mattis to make small changes without having to ask permission from the White House each time to speed up the process, officials say.

The Pentagon is also asking for NATO contributions as well.

In February, the top U.S. commander in Afghanistan, Gen. John Nicholson, told lawmakers on Capitol Hill he needed a “few thousand” more troops including from allies, less than two months after then-President Obama ordered roughly 1,500 U.S. troops out of Afghanistan at the end of December. Officials say the increase in forces in the coming weeks makes up for cut at the end of 2016.

Dunford was the top U.S. commander in Afghanistan from 2013-2014.

There are roughly 8,400 U.S. troops in Afghanistan right now. Unofficially, officials say that number is closer to 10,000.