Which one of thee following is not a member of ASEAN ?

The Association of Southeast Asian Nations (ASEAN) was established in 1967 by five founding members: Indonesia, Malaysia, the Philippines, Singapore, and Thailand [c1][t2]. Over the subsequent decades, the organization expanded to include Brunei Darussalam (1984), Vietnam (1995), Laos and Myanmar (1997), and Cambodia (1999), bringing the membership to ten [c1][t5]. Recently, Timor-Leste has been recognized as the 11th member state [t6]. While South Korea (Republic of Korea) maintains significant economic ties with the bloc through the ASEAN-Korea Free Trade Agreement (AKFTA) and participates in the 'ASEAN Plus Three' forum alongside China and Japan, it is a dialogue partner rather than a member state [c5][t2][t7]. Therefore, South Korea is not a member of ASEAN, whereas Cambodia, Malaysia, and Singapore are all official members [c1][t8].

Sources

1. [1] Contemporary World Politics, Textbook in political science for Class XII (NCERT 2025 ed.) > Chapter 2: Contemporary Centres of Power > 20 Contemporary World Politics > p. 20
2. [2] https://en.wikipedia.org/wiki/Member_states_of_ASEAN
3. [3] Indian Economy, Vivek Singh (7th ed. 2023-24) > Chapter 13: International Organizations > Regional Comprehensive Economic Partnership (RCEP) > p. 394