President Donald Trump is playing down Iran’s downing of an American drone, saying that it might have been a mistake executed by someone just being “loose and stupid”.

Trump told reporters Thursday that the shoot down of the drone was a “new wrinkle” in escalating tensions between the US and Iran a “fly in the ointment” in.

He was coy about whether the US would respond, saying only that "you'll find out."

He said he has a feeling that it was a mistake that a “general or somebody” made a mistake in shooting that drone down.

“I would imagine it was a general or somebody that made a mistake in shooting that drone down. And fortunately, that drone was unarmed. It was not ... there was no man in it and there was no... it was just it was over international waters, clearly over international waters. But we didn't have a man or woman in the drone. We had nobody in the drone.  Would have made a big difference. Let me tell you, would have made a big, big difference,” he said. 

But he added that Iran made a “big mistake” and that the US “will not stand for it.”