U.S. Secretary of State Mike Pompeo has made an unannounced trip to Iraq as Washington warns Iran against any action against American interests in the Middle East.

Pompeo was in Baghdad briefly Tuesday night before flying out.

Pompeo says his visit was meant to show U.S. support for "a sovereign, independent" Iraq, free from the influence of neighboring Iran. He met with Iraq's president and prime minister.

Pompeo's visit comes amid increasing tensions between Washington and Tehran. The U.S. is rushing an aircraft carrier strike group to the Middle East to deter or respond to any Iranian attack. U.S. officials have said there are indications Iran is planning to retaliate for the Trump administration's stepped-up sanctions on the country, although the threat information remains vague.