Washington DC - President Donald Trump on Sunday congratulated the leaders of Thailand and Cambodia on a ceasefire agreed the previous day after weeks of border clashes that have killed dozens.

"I want to congratulate both great leaders on their brilliance in coming to this rapid and very fair conclusion," said Trump, who has claimed credit for a previous truce that was broken earlier this month when the border conflict reignited.

In a post on his Truth Social platform, Trump called the eventual outcome "FAST & DECISIVE, as all of these situations should be!"

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He added that Washington, which has been involved in mediation efforts along with China and Malaysia, was "proud to help."

Ahead of talks with Ukrainian President Volodymyr Zelensky later on Sunday, Trump lauded his self-proclaimed role in ending world conflicts, saying "perhaps the United States has become the REAL United Nations."

"The United Nations must start getting active and involved in WORLD PEACE!"

Secretary of State Marco Rubio welcomed the Thailand-Cambodia ceasefire on Saturday, calling on both sides to "immediately honor this commitment."

At least 47 people were killed and more than a million displaced in three weeks of fighting that spread to nearly every border province on both sides, according to official tallies.

Announcing their agreement on Saturday, Thailand and Cambodia pledged to cease fire, freeze troop movements, and allow civilians living in border areas to return home as soon as possible.

Following the truce, China's top diplomat Wang Yi is hosting the Cambodian and Thai foreign ministers for two days of talks that began Sunday.

Wang told his Cambodian counterpart Prak Sokhonn that the ceasefire "has opened the process of rebuilding peace", according to a statement from Beijing's foreign ministry.

"Both sides should proceed step by step to promote a comprehensive and lasting ceasefire" and "rebuild mutual trust," Wang added.