The top U.S. general in Afghanistan on Wednesday left the door open to altering the plan to remove U.S. troops from the country, saying he doesn’t yet know what U.S. and Afghan officials can accomplish in the coming fighting season while focused on a new training mission.

Gen. John F. Campbell told the House Armed Services Committee that he wants to see how new “Train Advise and Assist Commands” (TAACs) do while working with senior Afghan military officials. The commands were established as part of the military support mission established at the beginning of the year as NATO ended its formal combat mission in Afghanistan.

“What I really want to make sure we can do is get through what we call a full fighting season — April through the late-September time frame — focused on train, advise and assist, plus our [counter-terrorism] mission,” Campbell testified. If U.S. troop levels drop to 5,500 by the end of the year, as planned, “that could potentially take our eye off focusing on train, advise and assist when we really need it.”

There are currently more than 10,000 U.S. troops in Afghanistan. Although the White House has backed the plan to pull out all but those 5,500 troops by the end of this year — plus a few hundred serving at the U.S. Embassy in Kabul — Afghanistan’s new president, Ashraf Ghani, and Defense Secretary Ashton B. Carter said during a joint appear in Kabul last month that the two countries are rethinking the pace of the drawdown.

The “TAAC” headquarters are in Jalalabad in the east, Kandahar in the south, Herat in the west and Mazar-e Sharif in the north, he said. Each one is commanded by a one-star coalition officer, and focused on training senior levels of the Afghan military.

Campbell cited an ongoing operation involving thousands of Afghan soldiers in southern Afghanistan’s Helmand province as an example of how the Afghan military has progressed.

“This is an operation that was entirely planned and led from the Afghan perspective,” Campbell said. “I took back-briefs on it about three weeks ago when I was down in Helmand…. I’ve never seen an Afghan operation that was that complex back-briefed to me and the senior leadership inside Afghanistan on the police and the army side. And the integration between the all the Afghan security pillars — the police, the army, the intelligence — was pretty remarkable.”