The Southeast Asian neighbors, who share a disputed 500-mile frontier, have long fought over the sovereignty of a 1,000-year-old temple.

Long-festering tensions over border territory have escalated into armed conflict between Cambodia and Thailand, leading to dozens of deaths on both sides and displacing tens of thousands of people.

Thailand has one of the best-equipped and trained air forces in Southeast Asia, with an estimated 46,000 personnel, 112 combat-capable aircraft, including 28 F-16s and 11 Swedish Gripen fighter jets, and dozens of helicopters.

Thailand favours bilateral negotiation rather than third-party mediation to resolve its military conflict with Cambodia, two Thai officials said, as fighting along their disputed border continued unabated.

The fighting has killed at least 14 people in Thailand, while Cambodia confirmed its first fatality on Friday.

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

Thailand’s military conflict with Cambodia is inflaming nationalist tensions at home and threatening embattled leader Paetongtarn Shinawatra, who had already been suspended as prime minister for her handling of the border dispute.

(Reuters) -Britain's foreign ministry on Thursday has advised against all but essential travel to parts of Cambodia and Thailand following the worst fighting between the countries in 13 years.