In his 4 January 1947 conversation with the United States Secretary of State George Marshall, Romania's Ambassador Mihai Ralea received an official American reproach for having "broken the spirit and letter" of the Moscow Conference and the Yalta Agreement. Although Ralea, a Ploughmen's Front member and possibly an ally of the Communists, expressed concern over the fact that the United States were reproving Romania, he also appealed to the United States not to allow the country to be left behind the Iron Curtain. In August 1946, Berry attested that Groza intended to tighten connections with the other countries in the Balkans and Eastern Europe, as the basis for a customs union. Giurescu compares this with the plan of a federation between Bulgaria and Yugoslavia, advocated by Georgi Dimitrov and Josip Broz Tito, which was frustrated by the opposition of Joseph Stalin, and discarded altogether following the Tito-Stalin Split.