There is no sense in providing MQ-9 Reaper unmanned aerial vehicles (UAVs) to assist Ukrainian forces in their war against Russian invaders because the drones are not survivable against Russian air defenses, senior defense officials said on Tuesday.

“Number one, it’s not survival,” Chairman of the Joint Chiefs of Staff Army Gen. Mark Milley told the Senate Armed Services Committee. “It’s big and slow. It’s gonna get nailed by the Russian air defense systems and, in terms of its capabilities, I’m not sure what it’ll get you beyond the smaller, faster, more nimble UAV systems that we are providing, as well as some other countries are providing.”

Defense Secretary Lloyd Austin also described Ukrainian airspace as “very hostile” given Russian air defense capabilities, adding that the Reaper isn’t “survivable” if used over Ukraine.

The defense leaders were responding to a question by Sen. Kevin Cramer (R-N.D.), who pointed out that the Air Force wants to retire 48 older MQ-9s and asked whether it “would be a reasonable system to offer Ukraine.”

The MQ-9 is built by General Atomics and is used for surveillance and reconnaissance missions, and to carry missiles and bombs to strike ground targets.