Ayeyawady-Chao Phraya-Mekong Economic Cooperation Strategy (ACMECS) is a political, economic, and cultural organization among Thailand, Laos, Vietnam, Cambodia, and Myanmar.

The objectives of this new initiative are to bridge the economic gap among these five countries and to promote prosperity in the sub-region in a sustainable manner. Such prosperity, it is expected, will not only benefit the four countries but also add value to ASEAN and its solidarity. It is hoped that a stronger Cambodia, Lao PDR, Myanmar, and Thailand will also mean a stronger ASEAN. In this way, the new cooperation framework is expected to act as a building block and move ASEAN forward at a more even pace, on the basis of self-reliance and shared prosperity.

Thailand is moving to shore up the Ayeyawady–Chao Phraya–Mekong Economic Cooperation Strategy as an alternative sub-regional forum to China’s Lancang Mekong Cooperative.