There was no immediate word from Iraq on the attack, the second in a week in the southern "no-fly zone." The Iraqi military said a U.S.-British airstrike on Tuesday at Iraqi air defense installations in Al-Muthana province injured four people.
Maj. Brett Morris, spokesman for the Joint Task Force Southwest Asia, said the planes struck Iraqi surface-to-air sites in Basra and Shahban, about 245 miles south of Baghdad.
Morris said that all aircraft, including U.S. F-16s and British Tornadoes, returned safely to bases.
Morris said Iraq had become "very active" in challenging coalition aircraft patrolling the southern "no-fly" zone, but did not provide any other details.
Since the beginning of the year, Iraq has fired more than 400 times at coalition aircraft compared to 300 times for all of last year, U.S. officials have said.
"This is a matter of concern for us ... but our pilots are wide awake to stay on top of their task," Morris said.
Iraqi air defense targets in southern Iraq have come under attack with increased regularity.
Pentagon spokesman Bryan Whitman stressed that the raids were not part of a new movement of U.S. forces in the wake of last week's attack on the United States. They were, he said, "in response to recent Iraqi hostile threats against (U.S. and British) coalition aircraft conducting routine monitoring of the southern no-fly zone."
The United States and Britain set up the "no-fly" zones after the Gulf war to protect anti-government forces in the north and the south.
Iraq considers the "no-fly" zones illegal and has vowed to shoot down any coalition planes.
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