The U.S. Embassy in Baghdad on Friday urged all citizens to depart Iraq immediately, hours after the United States killed Iranian Major General Qassem Soleimani and Iraqi militia commander Abu Mahdi al-Muhandis in an air strike.

"Due to heightened tensions in Iraq and the region, the U.S. Embassy urges American citizens to heed the January 2020 Travel Advisory and depart Iraq immediately. U.S. citizens should depart via airline while possible, and failing that, to other countries via land," it said in a statement.

Iran's Supreme Leader Ayatollah Ali Khamenei said on Friday that those who shed the blood of General Soleimani, commander of the Islamic Republic's Quds Force, and his companions "should await a tough revenge," Iranian state TV reported.

Iran's Islamic Revolutionary Guard Corps confirmed on Friday that Soleimani was killed in an airstrike on Baghdad International Airport.