CAMBODIA AND THAILAND
Length: 500 miles
Why it's so dangerous: Dozens killed and tens of thousands displaced on both sides of the border over disputed territory dating back to colonial times.
Background: For years, Cambodia and Thailand have fought over the Preah Vihear temple, situated along the border. Thailand argues that the area was never fully demarcated and blames a map drawn at the beginning of the 20th century during the French occupation of Cambodia for the lack of clarity. Following a lengthy dispute, the International Court of Justice in 1962 awarded the 11th-century Hindu temple to Cambodia. But the dispute over the 1.8-square-mile area around the holy site has never been resolved. Tensions between the two Southeast Asian neighbors have escalated in recent years, fueled in part by Cambodia's successful 2008 UNESCO application to have the temple declared a World Heritage site, something the Thai government backed at the time but has since been pushed by nationalist groups to oppose.
Today: Since 2008, skirmishes along the border have become a regular occurrence, with the most recent bout of violence breaking out April 22. On May 4, the two sides agreed to a cease-fire, but neither country has shown full confidence in the agreement, and both have heavily fortified the border with hundreds of troops. Tens of thousands of refugees have fled the area.
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