In separate clashes, US Navy F-14s and Air Force F-15s made radar contact with Iraqi aircraft which they say were in the no-fly zone, and fired at them. Iraq has said for a week that it was flying within the zone, although this was the first time the the allies have confirmed any sightings. But the Pentagon said yesterday there had been an increasing number of violations over the past two weeks.
The Iraqi aircraft were MiG-25 Foxbats, comparable to the F-15 although it is unclear how it would match up in air-to-air combat. The last clash between Iraqi aircraft and the US was in 1992, when an American F-16 shot down an Iraqi MiG-25.
The Iraqi air force was badly damaged during the Gulf War, losing 37 aircraft in air-to-air combat and 100 on the ground. A further 112 fled to Iran. What is left is still formidable in terms of numbers, but the standards of maintenance, training and morale are not known. The country has an estimated 200-250 fighters, but probably only half are operational.
It is by no means clear why the Iraqi air force has suddenly decided to show itself. According to one version of events, the aircraft were trying to lure the Americans into a trap by making them fly towards missile batteries. According to another, they were trying to sandwich the Americans, from above and below. Over a dozen Iraqi aircraft were involved - about the same number that the US fields over the no-fly zones.
The most obvious interpretation, from a Western viewpoint, is that Iraq is trying to provoke a confrontation. It has started firing surface-to- air missiles at allied aircraft. By posing a direct threat to allied airmen, it is tempting the US to strike once more at Iraqi targets, causing rising anger in Iraq's neighbours.
"We have looked at numerous options and have various plans that are available right now. If the [US] President were to see fit to take that type of action, we in fact have these kinds of plans on the shelf," General Hugh Shelton, Chairman of the Joint Chiefs of Staff said yesterday. If not, then they must be prepared for increasing risks to their air crews.
But there may be more to it. Washington clearly targeted strategic sites in southern Iraq during Operation Desert Fox, including the military and communications. It was, Iraq said, trying to cut off the area. Now, the State Department says there has been significant unrest in the south for at least two months, after the killing of two Shia Muslim clergymen there. And there is clearly increased tension in the air. It is possible that yesterday's episode was just part of a broader conflict that may be stirring over southern Iraq.