U.S. Central Command’s Gen. Frank McKenzie warned on Tuesday it will be challenging to continue fighting terrorism from afar in his first congressional testimony since President Joe Biden rolled out his Afghanistan exit plan.

Biden announced his plan for a full withdrawal of the remaining 2,500 U.S. troops there by Sept. 11 despite the Taliban’s flouting of several aspects of a peace deal signed with the Trump administration last February. Lawmakers have pointed to the fact that the Taliban has not broken with al Qaeda terrorists, and violence has risen in Afghanistan over the last year. Concerns also persist that the Afghan government will fall once U.S. military protection is withdrawn.