American warplanes have struck at air defenses in southern Iraq for the second time in less than a week.

Pentagon officials say Air Force and Navy jets attacked a surface to air missile site in Iraq's southern no-fly zone. The raid was smaller than last Friday's strike, which hit three targets and involved about 20 U.S. and British aircraft.

The Pentagon reports all the planes taking part in the latest attack Tuesday returned safely. So far, there is no damage assessment.

Officials say the strike was a response to past violations and provocations by Iraqi forces. The allies have enforced no-fly zones in southern and northern Iraq since the Persian Gulf war.

Baghdad considers the zones illegal and has recently stepped up its effort to shoot down the patrolling aircraft.