The deadly conflict on the Thai-Cambodian border pits a longtime United States ally with decades of experience against a relatively young armed force with close ties to China.

China has dismissed allegations that it was supplying weapons to Cambodia amid its ongoing border conflict with Thailand that has led to at least 33 people dying and hundreds of thousands displaced.

The latest flare-up started on Thursday, with intense fighting spreading across multiple border areas. Early Saturday, Thailand’s navy joined the army in repelling what it described as incursions by Cambodian troops at three points in eastern Trat province.