Four U.S. warplanes bombed two separate Iraqi military sites in the second such airborne missile strike this week, American military officials reported.

The actions Wednesday came after Iraqi forces had lobbed surface-to-air missiles at U.S. aircraft patrolling the skies over Iraq for the third time within a 15-day period, according to a statement issued by the U.S. Central Command headquarters in Tampa, Fla.

The command oversees U.S. military forces that monitor Iraq's southern "no-fly" zone. British aircraft also participate in the monitoring mission, established over southern and northern Iraq since shortly after the 1991 Gulf War.

"This action was taken to reduce the threat to the coalition aircraft patrolling the southern no-fly zone," the statement said.

"There have been no less than three attempts to destroy a coalition aircraft in the last 15 days," the statement said.

Two of the four U.S. planes struck an Iraqi aircraft and missile control center located near the city of Talil. Two other U.S. warplanes bombed an anti-aircraft missile system positioned near the city of Nasiriyah. Both strikes occurred around 5:15 p.m. EDT Wednesday, military officials said.

The Central Command statement said the anti-aircraft missile system was located south of the 32nd parallel, outside the area in which Iraq is supposed to have defensive military systems.

On Monday, U.S. warplanes bombed an Iraqi air defense site in southern Iraq after coming under attack by a surface-to-air missile.

Before that, U.S. aircraft had not attacked a target in southern Iraq since April 15.

The Central Command statement said Wednesday's attacks led to the destruction of the two Iraqi targets, but also said the assessments of the damage was continuing.

The statement did not identify the type of U.S. aircraft involved in the mission.

Iraq frequently tries to shoot down the allied planes patrolling the two zones. Baghdad considers the "no-fly" zones to be illegitimate violations of Iraqi sovereignty.