A fierce border conflict between Cambodia and Thailand has escalated, resulting in significant casualties and displacement. International concern has grown, prompting intervention from US President Donald Trump,

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

Of course, trouble at the 508-mile (817 km) shared border is nothing new. For over a century, Thailand and Cambodia have contested sovereignty at various undemarcated points in the thick jungle punctuated with culturally-significant temples albeit with scant strategic or economic value.