Despite the U.S. withdrawal from Southeast Asia after the Vietnam War, Thailand was still able to maintain its central role in regional politics because of the Cambodian issue. Thailand mobilized ASEAN support to apply pres-sure against Vietnam’s invasion of Cambodia in December 1978. This cam-paign brought about the international sanctions on Vietnam and its puppet government in Phnom Penh and a long process of international discussion about Southeast Asia throughout the 1980s. This regional episode also brought Beijing closer to Bangkok as de facto security allies against Vietnam, which gradually helped Beijing normalize its relations with other Southeast Asian states afterwards