But the fiery bout in Southeast Asia also marks a test for Washington's waning influence in a region viewed as a crucial theater in a geopolitical competition between the United States and China. "This crisis represents a critical test of American and Chinese influence in Southeast Asia,

At least 16 people have been killed and tens of thousands have been displaced as fighting extended to a second day.

Thailand and Cambodia have been exchanging heavy artillery fire over the border. The worst fighting in more than a decade stretched for a second day in an escalating border conflict that has killed at least 16 people.