In August 1968 a small group of pro-Moscow hardliners in the Czechoslovak Communist Party, led by Vasil Bilak, wrote two letters requesting urgent assistance from the Soviet Union to thwart the imminent "counterrevolution" in Czechoslovakia. Both letters were addressed to Leonid Brezhnev, the general secretary of the Soviet Communist Party (CPSU), and both were written in Russian to ensure that they would be read promptly. The first (and more important) letter was signed by Bilak and four of his colleagues: Drahomir Kolder, Alois Indra, Oldrich Svestka, and Antonin Kapek. Brezhnev later used the letter as a formal justification for the impending military invasion of Czechoslovakia.