By Nick Childs BBC Pentagon correspondent, Washington

The US military says aircraft patrolling the southern no-fly zone over Iraq have dropped leaflets warning Iraqis for the first time not to repair equipment and facilities previously hit by allied planes.

It was the fifth leaflet drop on southern Iraq in the last two months.

Previously leaflets warned Iraqi forces not to fire on patrolling US and British aircraft.

But this time the message was different - the 360,000 leaflets used in the latest operation were dropped on unmanned communications facilities which had already been struck.

Some of the leaflets warned the Iraqis not to repair the equipment there. The others said the no-fly zones are to protect the Iraqi people.

The zones remain controversial.

The Bush administration still describes Iraq's continued shooting at aircraft patrolling in them as unacceptable.

But administration officials have backed away from the idea that such incidents might form a pretext for wider military action under the new UN Security Council resolution on Iraq.

There was little support for that idea from US allies and a senior US defence official has told the BBC that the US military never saw that as an option.

Still, the leafleting of unmanned communications facilities is a sign of how important the Pentagon feels such sites are to Iraq's overall air defence capability - something which could be significant if there is to be a US-led military campaign against Baghdad.