Iran is helping the Houthi rebels in Yemen target U.S. Reaper drones, which has enabled the Houthis to shoot down or damage several of the massive, unmanned aircraft, say two U.S. officials.

Tehran was already supporting the Houthis with money, training and equipment, but in recent months the Iranians have also helped the rebels stop the MQ-9 Reapers, which are used for both intelligence collection and airstrikes. Reapers can carry Hellfire missiles and laser-guided bombs.

The Houthis…