Washington ? Aircraft from U.S.-British air patrols over southern Iraq bombed an Iraqi communications site, the sixth strike this month in retaliation for what the Pentagon says were hostile actions by Iraq.

The coalition planes used precision-guided bombs Sunday to hit a communications bunker at a military site in southern Iraq, according to a statement from U.S. Central Command. The statement said Iraq has fired surface-to-air missiles or anti-aircraft artillery at coalition aircraft 70 times this year.

“We fire back at those things we can find which seem appropriate,” Defense Secretary Donald H. Rumsfeld said Monday. “Clearly, one of the things that are appropriate is communications systems, because it’s the communications and the fiber optics that they’ve been putting in that enable them to cue a variety of radars and have a better success rate of tracking our aircraft.”

In Baghdad, the official Iraqi News Agency quoted an unidentified military spokesman as saying “enemy warplanes” bombed unspecified civil installations Sunday in Wassit province, which is 90 miles south of the capital. The spokesman gave no further information.

U.S. military officials say Iraq in recent months has stepped up its challenges to planes patrolling the no-fly zones in northern and southern Iraq that were set up after the 1991 Gulf War. Iraq says the no-fly zones are a violation of its sovereignty and often tries to shoot down the planes patrolling them.

Rumsfeld said the number of firing incidents is not unusual, adding that he expected them “on a weekly basis.”

“Our purpose would be to punish and to destroy things that are of military value” to Iraqi leader Saddam Hussein, Rumsfeld said.