The Soviet Union, which feared Western powers and the possibility of "capitalist encirclements", had little faith either that war could be avoided, or faith in the Polish army, and wanted nothing less than an ironclad military alliance with France and Britain that would provide a guaranteed support for a two-pronged attack on Germany; thus, Stalin's adherence to the collective security line was purely conditional. Britain and France believed that war could still be avoided, and that the Soviet Union, weakened by the Great Purge, could not be a main military participant, a point that many military sources were at variance with, especially Soviet victories over the Japanese Kwantung army on the Manchurian frontier. France was more anxious to find an agreement with the USSR than was Britain; as a continental power, it was more willing to make concessions, more fearful of the dangers of an agreement between the USSR and Germany. These contrasting attitudes partly explain why the USSR has often been charged with playing a double game in 1939: carrying on open negotiations for an alliance with Britain and France while secretly considering propositions from Germany.