Iranian officials signaled that fast trials and executions lay ahead for suspects detained in nationwide protests, while the Islamic Republic promised retaliation if the U.S. or Israel intervened in the domestic unrest. The threats emerged Wednesday as some personnel at a key U.S. military base in Qatar were advised to evacuate even as President Donald Trump made a series of vague statements that left it unclear what American action, if any, would take place against Iran. The Islamic Republic also shut its airspace to commercial flights early Thursday morning for several hours, without explanation.