Iran is bracing for a potential attack as the United States deploys key military assets, including an air carrier and additional bombers, to the Middle East. US President Donald Trump has threatened to strike the Islamic Republic over its bloody crackdown on anti-government protesters. If Trump authorizes military action, Tehran would be virtually powerless to stop an aerial attack, experts say. But that does not mean Iran cannot retaliate against US military and commercial assets in the region, experts say, citing Tehran's formidable arsenal of…