Beginning in August 1960 and extending into 1962, Laos was racked by political instability and civil war. Following a coup led by Captain Kong Le in the capital, Vientiane, Prince Souvanna Phouma was installed as Prime Minister. However, in December 1960, General Phoumi Nosavan responded with a successful counterattack in the capital and installed Prince Boun Oum as Prime Minister. Souvanna Phouma and Kong Le withdrew to the Plain of Jars, where they maintained a separate government under the Pathet Lao. While the United States and Thailand recognized Boun Oum's government, China and the Soviet Union supported Souvanna's. Efforts by the U.S., the Soviet Union, and Prince Sihanouk of Cambodia to mediate the civil conflict culminated in the International Agreement on the Neutrality of Laos, signed in Geneva in July 1962.