The White House has given Defense Secretary Jim Mattis the authority to set the troop levels in Afghanistan, two months after being given similar authority in Iraq and Syria, a U.S. official confirmed to CBS News' David Martin.

The move gives Mattis the ability to send more troops in, although it's unclear if Mattis intends to do so.

Mattis told Congress on Tuesday that the U.S. is "not winning in Afghanistan right now," and the enemy is surging.

"We need to correct this as soon as possible," Mattis said, but he said the U.S. would not have a new strategy until mid-July. Mattis said he would take steps to minimize the impact of the delay.

Get Breaking News Delivered to Your Inbox

The U.S. has about 8,400 troops in Afghanistan. Army Gen. John Nicholson, the top U.S. commander in Afghanistan, has told Congress that he could use an infusion of U.S. and allied troops to bolster support for the Afghan army.

Earlier this year, the Pentagon was considering a request for roughly 3,000 more troops, mainly for training and advising. That decision, however, has been stalled by the broader administration review of Afghan policy and a push for NATO to contribute more troops.

Three U.S. soldiers were killed and another wounded Saturday when they were attacked by an Afghan soldier, who was then killed. And two U.S. Army Rangers died in a April 27 raid on an IS compound in eastern Afghanistan. Officials were investigating whether they were killed by friendly fire in the opening minutes of the three-hour battle. Their deaths came just days after a U.S. Army special forces soldier was also killed in the region.

The Afghanistan war has been dragging on since October 2001, and the U.S.-led coalition ended their combat mission against the Taliban in 2014 but they are increasingly involved in backing up Afghan forces on the battlefield.

Asked what he hoped the situation in Afghanistan would look like a year from now, Mattis said violence would be down, government corruption would be reduced and the Taliban would be "rolled back," with less freedom of movement on the battlefield.

Marine Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, added that he hoped Afghan troop casualties would be lower a year from now. And he said a key to that will be the need for the U.S. to assist the Afghans in planning operations and providing aviation support while Kabul works to increase its combat air power.

McCain, however, listed the names of the three 101st Airborne Division soldiers who were killed Saturday and said, "Let's not ask these families to sacrifice any further without a strategy which we can then take and implement and help you. I'm fighting as hard as I can to increase defense spending. It's hard when we have no strategy to pursue."

On separate issues, Mattis and Dunford were asked about the Mideast diplomatic rift and alleged Russian meddling in last year's U.S. presidential election.

On Russia, Mattis said, "This sort of misbehavior has got to face consequences, and not just by the United States but more broadly." He added that the Trump administration is working on a comprehensive cyber defense strategy, but in the meantime the U.S. has enough understanding of Russia's cyber actions to defend against them.

Sen. Elizabeth Warren, D-Mass., asked Dunford whether the diplomatic rift between Qatar and several of its neighbors, including Saudi Arabia, is impeding U.S. military operations, given that the U.S. uses Qatar's al-Udeid air base as a critical air operations center for the wars.

"It is not," Dunford said.