Trump knows if the U.S. responds with military force to quell the rag-tag mob that stormed/destroyed parts of the heavily fortified U.S. embassy it will drag the U.S. into another mid-East quagmire he often criticized his predecessors for, and will be the end of his presidency. So Trump will allow the U.S. to be embarrassed and will threaten via Twitter, which Iran laughs at and continues to use proxies to prod the U.S. into a conflict that could have been avoided had Trump not pulled out of the Iranian nuclear weapons Agreement reached by Pres Obama + FIVE other nations, and instead imposed sanctions on Iran.