Cambodia and Thailand exchanged fire across their disputed border for a fourth day on Sunday, hours after US President Donald Trump announced the two Southeast Asian nations had agreed to ceasefire talks and threatened continued fighting would jeopardize their trade deals with Washington.

Thailand expressed cautious support. Phumtham thanked Trump and said that Thailand agreed in principle to a ceasefire but stressed the need for “sincere intention” from Cambodia, the Thai Foreign Ministry said. Phumtam called for swift bilateral talks to discuss concrete steps toward a peaceful resolution, it said.

President Trump said on Saturday that both countries had agreed to a halt in the fighting. But on Sunday morning, skirmishes erupted once more.