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,

The U.N. Security Council planned to hold an emergency meeting in New York on the crisis, while Malaysia, which chairs a regional bloc that includes both countries, called for an end to hostilities and offered to mediate.

In Thailand, clashes in the Ubon Ratchathani and Surin provinces wounded dozens and displaced more than 100,000 civilians. Some 1,500 families in Cambodia's Oddar Meanchey province have been evacuated. Malaysia's Prime Minister Anwar Ibrahim says he has appealed to leaders of both countries for an immediate ceasefire.