The US was hoping to achieve air superiority over Yemen within 30 days, officials said and degrade Houthi air defense systems enough to begin a new phase focusing on ramping up intelligence, reconnaissance and surveillance of senior Houthi leaders in order to target and kill them, the officials said.

But the platforms best suited to conduct that persistent effort, the MQ9 Reaper drones, keep getting shot down, the officials explained. In fact, the Houthis are only getting better at targeting them, the officials said.