As World War II ended, the French found themselves embroiled in the First Indochina War. On 23December 1950, the United States signed the Pentalateral Treaty with France, Cambodia, Laos, and Vietnam binding them to financially support the French effort. From that point onwards, the U.S. would fund an ever greater proportion of the French war effort; by 1952, it was funding about a third of the French budget for the war. Beginning as early as 6May 1953, the U.S. Central Intelligence Agency (CIA) used its proprietary airline, Civil Air Transport, for combat supply drops in support of the French Army in Laos. Following the North Vietnamese 1953 invasion of Laos and the French defeat at Dien Bien Phu, the independence of the Kingdom of Laos was confirmed by international treaty on 20July 1954. In December 1955, the secretive Programs Evaluation Office was established in the American embassy in Vientiane, Laos to help the Royal Lao Government battle the communist insurgency.