The top U.S. commander in Afghanistan said Tuesday the death of Al Qaeda-linked leader Mullah Omar could drive Taliban fighters into the arms of ISIS – or to the negotiating table.

General John Campbell, in Washington this week to discuss the situation in Afghanistan – where Taliban attacks are on the rise -- also told the Brookings Institution, "there's no way...the Taliban can overthrow the Afghan government."

However, Campbell has previously warned that ISIS now poses a threat to U.S. forces in Afghanistan, a change in tone from a few months ago when he called the group's intentions aspirational.

The visit by Campbell, who commands nearly 10,000 U.S. troops in Afghanistan, comes one week after the death of Mullah Omar was reported publicly for the first time, even though the Al Qaeda-linked commander died two years ago of liver or kidney problems.

The White House announced a halt to major combat operations in Afghanistan last December, but just last month the U.S. military carried out 11 drone strikes in one Afghan province that borders Pakistan.

Campbell also said the Afghan army continues to lose trained soldiers at an alarming rate.

"They lose probably in the neighborhood of 4,000 per month,” Campbell said. “And a lot of that you would think is battlefield casualties, and that is the greatest majority, that is not the case. The biggest case is folks that go AWOL, absent without leave."

 

Jennifer Griffin currently serves as a national security correspondent for FOX News Channel . She joined FNC in October 1999 as a Jerusalem-based correspondent. You can follow her on Twitter at @JenGriffinFNC.

Lucas Tomlinson is the Pentagon and State Department producer for Fox News Channel. You can follow him on Twitter: @LucasFoxNews