The occupation of the airport was an aggressive move by Russia after they felt they had been double-crossed in the negotiations. Clark wanted to prevent it. The WW3 part is a personal estimation of Jackson that the situation would get out of hand. Clark and Solana had a different view. But the troops in the area were mainly British.
The Russian move was aggressive? Interesting you don't qualify NATO's moves as being aggressive. The Russians, who were instrumental in negotiating a deal between NATO and Milosevic, had an agreement with NATO that they would "deploy" their forces in the North of Kosovo. To thank the Russians for their mediation, NATO later reneged on this agreement (surprising of such a worthy organization).
The Russian move was aggressive? Interesting you don't qualify NATO's moves as being aggressive.
The occupation of the airport was an aggressive move by Russia after they felt they had been double-crossed in the negotiations.