WASHINGTON -- NATO warplanes pummeled targets throughout Yugoslavia yesterday and hit President Slobodan Milosevic's party headquarters last night, as Western leaders moved to isolate Milosevic and signal to other Serbian leaders that their nation's only hope for peace and recovery might be his removal from power.

British Prime Minister Tony Blair fired the first verbal salvo at Milosevic, declaring that NATO would "carry on until he does step down."

Secretary of State Madeleine K. Albright quickly stepped in to say that Blair had intended to say "back down." But Albright applied her own verbal pressure, saying flatly that NATO would not negotiate with Milosevic.

"We believe that the Serb people would be better served by having a democratically elected government that represents their values," Albright said.

NATO's air campaign entered its fourth week yesterday, with alliance leaders insisting that the airstrikes would achieve NATO's objectives.

As he awarded former German Chancellor Helmut Kohl the Presidential Medal of Freedom, President Clinton spoke of a Europe "where nationhood is a source of pride, not a crucible of conflict."

"It is to protect that vision that the NATO allies are in Kosovo today, to defeat the cynical vision embodied by Mr. Milosevic, in which the most primitive hatreds and brutal oppression are more important than mutual respect and common progress," Clinton said.

But NATO leaders conceded that the campaign has been powerless to protect hundreds of thousands of Kosovar Albanians who have been driven from their homes but have not reached safety beyond the province's borders.

Party headquarters hit

A NATO air attack on Belgrade early today hit the headquarters of Milosevic's Socialist Party, setting it afire. The building, the USCE Business Centre, also houses the Kosava radio and television station, run by Milosevic's daughter Marija, and another television station, Pink, run by Zeljko Mitrovic, a prominent member of the United Left Party, led by Milosevic's wife, Mira Markovic.

Yugoslav media said NATO also struck Novi Sad's last remaining bridge over the Danube last night, and reported explosions near Serbia's second-largest city. Tanjug said two civilians died as NATO planes bombed industrial and communications targets in at least 10 towns in central and southern Serbia on Monday night and yesterday.

Daylight raids yesterday pounded the provincial capital, Pristina, and other parts of Kosovo, targeting troops and tanks. NATO planes bombed targets near Kosovo's Belacevac coal mine at least four times yesterday, the state-run Tanjug news agency said. The mine supplies coal for a Pristina power station that provides most of Kosovo's electricity.

Pressure beyond Serbian borders continued to mount. Croatia's state-run news agency reported that up to 300 Yugoslav soldiers entered the United Nations-monitored demilitarized zone that separates Croatia from Serbia. Serbian forces clashed with Albanian troops at an Albanian border post in the first battle between the two countries' forces.

New atrocities alleged

And the deputy prime minister of Montenegro, a pro-Western republic in the Yugoslav federation, said that Yugoslav soldiers had killed "at least six" Kosovar refugees inside Montenegro. The Serbian news agency Beta said Yugoslav forces had killed four members of the rebel Kosovo Liberation Army inside Montenegro.

NATO officials reported new evidence of atrocities, saying Serbian forces were raping ethnic Albanian women, using tear gas to drive Albanians from homes in Pristina, and using Albanian men as human shields around Serbian tanks.

Jamie P. Shea, NATO's civilian spokesman, said the alliance was investigating reports of 700 Kosovar Albanian boys being used either as human shields or as blood banks for injured Serbian soldiers.

"It's extremely depressing that human beings are used as pawns on this type of macabre and rather Machiavellian chess board," Shea said.

U.S. officials continued to press for a blockade of Yugoslavia to halt the resupply of fuel to Serbian forces, against opposition from some NATO allies, such as France. Defense Secretary William S. Cohen expressed confidence that he would secure an agreement to cut off fuel supplies to Yugoslavia this weekend, when the leaders of NATO's 19 nations will gather in Washington for the alliance's 50th anniversary summit.

"It's important that all sources of resupply of fuel and energy be eliminated," Cohen said.

Milosevic's future as a Yugoslav leader has been a source of diplomatic contention since the mid-1990s, when U.S. and European leaders negotiated an accord with the Serbian strongman to end the war in Bosnia. NATO diplomats have resisted declaring Milosevic a war criminal, leaving open channels to negotiate an acceptable peace for Kosovo with him.

Removing Milosevic

But NATO leaders went further yesterday to signal that Milosevic would have to go, edging to the point where negotiations with him would be politically impossible. British Foreign Secretary Robin Cook said British intelligence had taken the "rare step" of releasing intelligence material to the War Crimes Tribunal in The Hague, documenting atrocities.

"We are determined that those responsible for turning Kosovo into a slaughterhouse should be brought to justice," Cook said.

A Clinton administration official said the United States was making similar disclosures.

Asked whether Milosevic had to be removed, Albright told reporters yesterday: "President Milosevic is responsible for the 'ethnic cleansing' and all the depredations that are taking place. We have questioned how he is going to continue as the War Crimes Tribunal keeps working."

Besides the stick they have been wielding for four weeks, administration officials also held out a carrot to Serbian forces who might rise up against Milosevic. Albright pledged an extensive effort to rebuild Kosovo once the airstrikes cease, but she kept vague the U.S. intentions about reconstructing the rest of Serbia.

Such economic aid may be contingent on Milosevic's removal, White House aides hinted.

As those diplomatic maneuvers continued, the air war was poised to enter a more perilous phase. About a half-dozen Apache helicopters arrived in Albania late last night, according to a White House official, the vanguard of 24 Apaches expected by tomorrow.

The carrier USS Enterprise steamed through the Suez Canal yesterday with three other warships on its way to join the carrier USS Theodore Roosevelt and French and British carriers. Their arrival will substantially boost the number of planes in action in the area.

Signs of spreading

Meanwhile, the war continues to show signs of spreading. As NATO leaders prepared for the NATO summit in Washington this weekend, U.S. officials put out the word that Milosevic would try something to test the alliance's resolve, perhaps by trying to destabilize neighboring countries.

Such moves may already be under way. An Albanian soldier was injured in a six-hour skirmish that European border monitors witnessed near the remote northern outpost of Quafe E Prushit, said Andrea Angeli, a spokesman for the Organization for Security and Cooperation in Europe.

In a visit to Paris, President Rexhep Meidani of Albania vowed that the Albanian army would respond to further incursions by Serbian forces.

NATO Secretary-General Javier Solana said he could not confirm a report that Yugoslav troops had entered a U.N. buffer zone on Croatia's border.

Reuters news service contributed to this article.

Pub Date: 4/21/99