President Joe Biden is under increasing pressure to respond in a way that stops these attacks for good. Iran-backed militants have targeted US military facilities in Iraq and Syria over 160 times since October, and several Republican lawmakers have called for the US to hit inside Iran directly to send a clear message.

But the biggest challenge now for the Biden administration is how to respond to the drone strike – the deadliest attack on US forces in the region since the bombing at Abbey Gate killed 13 US service members in the closing days of the Afghanistan withdrawal – without sparking a regional war.