by the PRRI forces. That attack also laid bare that the PRRI was receiving military aid from the United States, given the large amount of US-made equipment abandoned by the PRRI forces which had taken flight. The United States Government, especially the CIA (see CIA activities in Indonesia) had covertly supported the rebel PRRI Government in 1958, despite some dissent in the agency from Desmond Fitzgerald. With the Americans posturing to become directly involved in the crisis, General Nasution conducted surprise amphibious assaults on rebel cities in Sumatra during March 1958. With the military balance swiftly swinging in favour of the Central Government in Jakarta during the period March–May 1958, and the fact that Lieutenant Colonel Husein had little choice but to pursue a strategy of withdrawal and guerrilla warfare which would make it difficult for the United States to publicly recognise the PRRI, the United States had to reconsider its previous policy assessment that the break-up of Indonesia and emergence of a Communist government was likely. The Pope incident on 18 May 1958 signalled the beginning of the end of the CIA's program of covert support to the PRRI, with the US shifting its support back towards Sukarno and the Central Government as the anticipated victor from the conflict. Surrender Although the conflict dragged on over the next three years, the government forces were successful in pushing the PRRI into the jungle and mountains, and retook several strongholds, including Kototinggi where the PRRI leadership was headquartered. General Nasution, who was leading the government forces, launched Operasi Pemanggilan Kembali (Operation Call Back) at the end of 1960 to take advantage of internal rifts within the PRRI. The main objective of which was to persuade the army officers supporting the PRRI to surrender themselves, because once there was no longer military support, the civilians would also follow suit. Small numbers of PRRI troops began surrendering from April 1961, while the majority did so in the middle of 1961. The last vestiges of the PRRI held out for a few more months before the final surrender by Mohammad Natsir, who was the last of them, on 28 September 1961. Legacy One of the most significant outcomes of the conflict was the establishment of Foreign Relations of the Soviet Union to the Indonesian Government. As the crisis had unfolded, the Indonesian Government had approached the American Government for arms to combat the rebel