Churchill observed that an "Iron Curtain" had been drawn across Europe, separating the east from the west. In September 1947, a meeting of East European communist leaders was held in Szklarska Poręba, Poland, from which was formed Cominform to co-ordinate the Communist Parties across Eastern Europe and also in France and Italy. Stalin did not personally attend the meeting, sending Zhdanov in his place. Various East European communists also visited Stalin in Moscow. There, he offered advice on their ideas; for instance he cautioned against the Yugoslav idea for a Balkan federation incorporating Bulgaria and Albania. Stalin had a particularly strained relationship with Yugoslav leader Josip Broz Tito due to the latter's continued calls for Balkan federation and for Soviet aid for the communist forces in the ongoing Greek Civil War. In March 1948, Stalin launched an anti-Tito campaign, accusing the Yugoslav communists of adventurism and deviating from Marxist–Leninist doctrine. At the second Cominform conference, held in Bucharest in June 1948, East European communist leaders all denounced Tito's government, accusing them of being fascists and agents of Western capitalism. Stalin ordered several assassination attempts on Tito's life and contemplated invading Yugoslavia.