US forces ready to resume combat operations against Iran if ordered

US forces are ready to resume combat operations against Iran if ordered, Washington's top military officer said Tuesday, as the Pentagon threatened a "devastating" response to Iranian attacks on commercial shipping in the Hormuz strait.The warnings came after Iran's powerful chief negotiator said Tehran "had not even started yet" in the crucial trade route, after a spate of attacks by both sides on Monday threatened to reignite the Middle East war.