NATO said yesterday it had launched its heaviest air raids so far and told Yugoslav President Slobodan Milosevic he must accept five key demands before the alliance considers stopping its bombing campaign.
The alliance said it would accept nothing less than full Yugoslav compliance with its conditions for a Kosovan settlement.
On Tuesday NATO rejected as "insufficient" the unilateral ceasefire announced by Belgrade and made clear yesterday it wanted Mr Milosevic to provide further guarantees.
"In recent hours, NATO leaders have put five key questions to President Milosevic which were not answered yesterday and to which we believe an answer is urgently necessary if NATO is to stop air operations," the alliance spokesman, Mr Jamie Shea, told a news conference.
These were:
Is Milosevic prepared for a verifiable cessation of all combat activities and killings?
Is he prepared to withdraw military, police and paramilitary forces from Kosovo?
Is he prepared to agree to the deployment of an international security force?
Is he prepared to permit the return of all refugees and unimpeded access for aid?
Is he prepared to put in place a political framework for Kosovo on the basis of agreement of the Rambouillet accords? Mr Shea said NATO foreign ministers would meet in Brussels next Monday to "underscore at high level NATO's resolve and determination to see its objectives fulfilled in the current Kosovo crisis".
NATO reported its aircraft had flown 439 sorties in the past 24 hours, the largest number in any one day since raids started on March 24th. It had also launched the largest number of bombing missions to date, hitting 28 "target groups", the military spokesman, Air Commodore David Wilby, said.
Commodore Wilby said alliance aircraft hit an armoured column in south-western Kosovo on Tuesday in its "first major breakthrough" against Yugoslav ground forces.
US A-10 Thunderbolts and British Harrier aircraft hit the column of as many as 12 vehicles on Tuesday afternoon as it moved along the road between Decani and Djakovica in south-western Kosovo, he added.
"This was our first major breakthrough against armoured forces in the field. We were able to locate and attack several units," Commodore Wilby said. "In one attack we were able to drop weapons on a column of between seven and 12 vehicles with complementary visual evidence of success from the cockpit."
While NATO has been able to demonstrate the effectiveness of air strikes against static military and infrastructure targets such as bridges throughout the two-week-old campaign, this was its first reported strike on forces on the ground engaged in the mass expulsion of Kosovo Albanians.
Allied commanders have been under pressure to strike directly at Yugoslav forces operating in Kosovo, where a NATO spokesman said some 50 villages had been burned by troops in the past four days.
Commodore Wilby showed a graphic sketch of the attack on the convoy but no cockpit video. He explained that "area weapons" had been used in the low-level strike, and initial confirmation of success came from pilots in follow-up aircraft.
French Super-Etendards and Jaguars also took part in ground attacks on targets in Kosovo on Tuesday but French sources declined to say whether they were involved in the successful raid on the armoured convoy.