Trump calls Iran's shooting down of U.S. drone fly in ointment

President Donald Trump on Thursday called Iran's shooting down of a U.S. military drone a new fly in the ointment and said it could have been a mistake.

Trump told reporters in the Oval Office that the drone was unarmed and clearly in international waters and that it could have been shot down by someone who was "loose and stupid."

"I think probably Iran made a mistake - I would imagine it was a general or somebody that made a mistake in shooting that drone down," Trump said during an appearance with Canadian Prime Minister Justin Trudeau.