It is conducted the study of regional challenges in Southeast Asia. The material is the texts of the official websites of the Thai government, the Ministry of Foreign Affairs of Thailand, ASEAN, the Embassy of Thailand in the countries of South-East Asia (Southeast Asia). An overview of the problem of separatism is given in the example of Thailand. Particular attention is paid to the essence of separatism in Thailand and the role of Thailand and the ASEAN countries in solving this problem. It is considered in detail that today the ASEAN countries have begun to play an important role in solving regional problems and creating a more stable region. Thailand is directly confronted with the problem of separatism. It pays much attention to solving this issue together with neighboring countries on the basis of international and regional cooperation. The work shows that every Thai government is trying to solve and restore the problem of separatism in the south by peaceful dialogue and peace agreement and cooperation. However, at present the very problem of separatism in the south of Thailand still exists.