Unmanned aerial vehicles, or drones, have become one of the weapons most closely associated with the global war on terror.

Hundreds of U.S. drones, also known as remotely piloted aircraft, of various types have spent countless hours tracking terrorists and providing American and coalition troops with early warning.

Drones have also attracted scrutiny for their use in killing enemy fighters with precision strikes — strikes that have often killed innocent civilians as well.

But as the U.S. military prepares for a conflict with countries deemed “peers” or “near-peers” — namely China or Russia — the days of drones dominating the air might be coming to an end.