After the Japanese invasion in September 1940, the French were forced to allow the Japanese to set up military bases. This seemingly subservient behavior convinced the regime of Major-General Plaek Pibulsonggram, the Prime Minister of the Kingdom of Thailand, that Vichy France would not seriously resist a confrontation with Thailand. In October 1940, the military forces of Thailand initiated border skirmishes across the border with Indochina, which escalated into Franco-Thai War.