The six countries also adopted two major documents, namely the Five-Year Action Plan (2018-2022) and the Phnom Penh Declaration at this year's meeting.

In the declaration, the leaders stressed the vision and importance of the LMC in contributing to the socio-economic development of sub-regional countries and enhancing the well-being of their peoples, narrowing the development gap among countries, supporting the ASEAN Community building as well as advancing South-South cooperation and enhancing the implementation of the United Nations 2030 Agenda for Sustainable Development.

The meeting, co-chaired by Cambodian Prime Minister Samdech Techo Hun Sen and the Chinese premier, also released the second batch of cooperative projects and reports of the six Joint Working Groups on the key priority areas.

Initiated by China in 2014, the framework spans connectivity, production capacity, cross-border economic cooperation, water resources management, and agriculture and poverty reduction, benefiting dozens of millions of people living on the waterway.

The first LMC leaders' meeting was held in Sanya of China's Hainan Province in March 2016, when the goal of building a community of shared future of peace and prosperity for the LMC countries was endorsed.

The Lancang River originates on the Qinghai-Tibet Plateau in southwest China. It is called the Mekong River as it flows through Myanmar, Laos, Thailand, Cambodia and Vietnam before emptying into the sea.