An American MQ-9 Reaper drone crashed off the coast of Yemen after apparently being struck by a missile fired by Iran-backed Houthi rebels, the Pentagon said Tuesday. It is the second time an MQ-9 – which can be used for both surveillance and strikes – was lost near Yemen in recent months, with US officials confirming last year that another was downed by the Houthis. The apparent shoot-down came the same day that the rebels targeted two US-owned merchant vessels as they continue their campaign of attacks on shipping in the area. “On February 19, a US MQ-9 was downed or went down off the coast …