In 1963, Indonesia opposed the British decolonisation initiative on the formation of Malaysia, arguing that it was the western imperialist move to block Indonesian influence. This led to an undeclared war popularly called "Konfrontasi" that took place between 1963 and 1966. This tension was marked by the infiltration of Indonesian forces into Northern Borneo. The conflict lasted nearly four years; however, following General Suharto's replacement of Sukarno, Indonesian interest in pursuing the war with Malaysia declined, and combat eased. Peace negotiations were initiated during May 1966 before a final peace agreement was ratified on 11 August 1966.