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.

Following up on calls by President Trump, Secretary of State Marco Rubio spoke with his counterparts in both countries. But on Sunday morning, skirmishes erupted once more.

The leaders from both countries are set to meet on Monday to talk about a ceasefire. Thailand’s foreign minister said his country agrees in principle to have a ceasefire in place.