The killing of a top commander of Iran’s Revolutionary Guard in a targeted strike by the United States set off a cascade of criticism, tough talk and jitters, extending from the halls of Congress and Twitter to the Middle East and the oil futures market.

The commander, Maj. Gen. Qassim Suleimani, died early Friday in a bombing attack at the Baghdad International Airport, the Pentagon said.

President Trump punctuated the significant military action by posting an image of the American flag on Twitter without any text.