"Out of an abundance of caution we recommend American citizens shelter in place until further notice," the U.S. Embassy in Doha, Qatar, said Monday amid concerns about retaliation from Iran.

Qatar said on Monday it had shut down its airspace temporarily, hours after U.S. and British authorities contacted their citizens there recommending that they shelter in place until further notice.

The message comes as tensions are high in the Middle East after the U.S. bombed Iranian nuclear sites on Sunday.