"The U.S. already flunked the test and that should be a wakeup call," a former senior U.S. State Department official told Newsweek.

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 UN Security Council held an emergency closed-door meeting Friday in New York. Malaysia, which chairs the 10-nation regional bloc that includes both countries, called for an end to the hostilities and offered to mediate.

By Shoon Naing SURIN, Thailand (Reuters) -Six-year-old Sunisa Chanprakhon was looking forward to running in her school sports day in their Thai border village on Thursday when explosions shattered the morning calm.