The Pentagon is continuing to determine whether a HARM missile aimed at an Iraqi missile site by a U.S. Air Force F-16 earlier this week hit its target.

"We're still looking. I don't believe any damage has been found so far," Defense Department spokesman Kenneth Bacon said at a Pentagon briefing.The F-16 targeted the Iraqi site with an air-to-ground missile as a defensive measure after the site threatened British Tornadoes patrolling the southern "no-fly" zone in Iraq. It was the first time a U.S. jet has fired on an Iraqi radar site since November 1996.

Bacon said no additional threats have been detected since the incident occurred Tuesday.

"Secretary (William) Cohen said that he hoped this was an isolated incident, and it appears that it has been that," Bacon said.

Because a HARM missile hones in on an opponent's radar signal, it can miss the target if the radar is turned off. The missile could have landed in a reservoir, as the Iraqis have claimed, Bacon said, leaving little chance for detecting exactly where it landed.

There has been no explanation for the threat, and Pentagon officials are not certain whether it even was a purposeful targeting of the allied aircraft, he said.

"We don't have a good explanation for why it occurred," he said.