US threats to impose “the toughest sanctions in history” to force Iran to buckle to its demands after nearly six months of war have raised the prospect of

Iran warns of a devastating response as the US prepares tougher sanctions, while falling oil flows through Hormuz raise concerns over global energy supplies.

By Jana Choukeir, Eman Abouhassira and Susan HeaveyDUBAI/WASHINGTON, Aug 21 (Reuters) - Iran said on Friday that its response to any new U.S. threats would be "devastating" after…