Following the end of the Malayan Emergency in 1960, the predominantly ethnic Chinese Malayan National Liberation Army, the armed wing of the MCP, retreated to the Malaysian-Thailand border where it regrouped and retrained for future offensives against the Malaysian government. A new phase of communist insurgency began in 1968. It was triggered when the MCP ambushed security forces in Kroh–Betong, in the northern part of Peninsular Malaysia, on 17 June 1968. The new conflict coincided with renewed tensions between ethnic Malays and Chinese following the 13 May Incident of 1969, and the ongoing conflict of the Vietnam War.