The Korean War was an increase of border clashes between two rival Korean governments (each of which was supported by external powers). Each Korean government was trying to topple the other through political and guerilla tactics. Some may refer to it as a civil war. Though many other factors were at play. South Korea filed to strengthen their cause in free elections held in May 1950. The refusal of South Korea to hold new elections per North Korean demands was also a factor. The communist North Korean Army moved south on June 25, 1950. It was an attempt to reunite the Korean peninsula which had been formally divided since 1948. The conflict was then expanded by the United States and the Soviet Union's involvement as part of the larger Cold War. The main hostilities were during the period from June 25, 1950 until the armistice was signed on July 27, 1953.