"Iran will be held fully responsible for lives lost, or damage incurred, at any of our facilities. They will pay a very BIG PRICE! This is not a Warning, it is a Threat," Trump wrote on Twitter hours after protesters angry about U.S. air strikes on Iraq hurled stones and torched a security post at the U.S. Embassy in Baghdad."The U.S. Embassy in Iraq is, & has been for hours, SAFE! Many of our great Warfighters, together with the most lethal military equipment in the world, was immediately rushed to the site," Trump said.