WASHINGTON -- Iraq fired on U.S. and British warplanes patrolling a no-fly zone Friday, an act the United States considers a breach of a U.N. Security Council resolution, officials said.

Coalition warplanes bombed an Iraqi air defense site in retaliation for the firing, a Pentagon statement said.

It was the first coalition strike on Iraq since Iraqi President Saddam Hussein's government accepted the Security Council resolution demanding that he disarm and allow inspectors to search for chemical, biological and nuclear weapons.

A "material breach" of the resolution could be reported to the Security Council for new debate -- and possibly used as justification for U.S.-led military action to topple Saddam's government. The U.S. official who said the government considers the firing a material breach could not say whether or when American officials would raise the issue with the United Nations.