Fighting between the Southeast Asian neighbours erupted over the weekend along their 800km frontier, with both sides exchanging artillery fire and Thailand using F-16 fighter jets after accusing Cambodia of firing rockets into civilian areas.

“Tomorrow I’ll have to make a phone call” to both countries, Trump said at an event Tuesday evening in Pennsylvania.

“Who else could say, ‘I’m going to make a phone call and stop a war of two very powerful countries,’” he said. “We’re making peace through strength.”

Trump threatened the two nations with trade restrictions to stop fighting in July – which left dozens dead – and in October oversaw the signing of the so-called Kuala Lumpur Accords that sketched out a path to peace, as well as trade deals with both countries.

The tensions between Thailand and Cambodia have ebbed and flowed for decades, often fuelled by the nationalist imperatives of their leaders at the time. In the latest outbreak that began on the weekend, Cambodia and Thailand are trading barbs over who’s at fault and accusing each other of escalation.

US secretary of state Marco Rubio released a statement Tuesday strongly urging the “immediate cessation of hostilities, the protection of civilians, and for both sides to return to the de-escalatory measures” outlined in the Oct 26 pact.