The early track record of the CIA was poor, with the agency unable to provide sufficient intelligence about the Soviet takeovers of Romania and Czechoslovakia, the Soviet blockade of Berlin, and the Soviet atomic bomb project. In particular, the agency failed to predict the Chinese entry into the Korean War with 300,000 troops. The famous double agent Kim Philby was the British liaison to American Central Intelligence. Through him the CIA coordinated hundreds of airdrops inside the iron curtain, all compromised by Philby. Arlington Hall, the nerve center of CIA cryptanalysisl was compromised by Bill Weisband, a Russian translator and Soviet spy. The CIA would reuse the tactic of dropping plant agents behind enemy lines by parachute again on China, and North Korea. This too would be fruitless.