What to know about a border rift that goes back more than a century

A Cambodian BM-21 multiple rocket launcher returns from the Cambodia-Thai border as Cambodian and Thai troops exchanged fire in a new round of clashes in Preah Vihear province yesterday. Thailand's Army said three civilians were wounded in a Cambodian rocket strike as the two countries' militaries clashed again in an escalating row over a disputed border. The neighbours are locked in a bitter spat over an area known as the Emerald Triangle, where the borders of both countries and Laos meet, and which is home to several ancient temples. Photo / AFP

Long-simmering tensions between Cambodia and Thailand erupted into open conflict yesterday as Thailand launched airstrikes at Cambodian targets along their disputed border.

The rift goes back more than a century. Here’s the history behind it.

What’s the cause of the Cambodia-Thailand conflict?

Relations between the Southeast Asian neighbours have been contentious since 1907, when the French colony of Cambodia and the independent Kingdom of Siam (as Thailand was known until 1939) signed a treaty delineating the 500-mile (800km) border between them.

The problem: The treaty’s map differed from its text - most notably, it left Preah Vihear, an 11th century temple of deep significance to both countries, in French territory.

Preah Vihear became a significant sticking point. During World War II, Japanese-allied Thailand seized the temple, then surrendered it to French Cambodia following the defeat of the Axis powers.

In 1954, as a newly independent Cambodia was emerging, Thailand capitalised on the moment to retake it.

Cambodia took the dispute to the International Court of Justice, where it argued that the 1907 French map proved its sovereignty over the temple.

The court agreed, ruling in 1962 that it belonged to Cambodia. Thailand accepted the decision and withdrew its troops.

In 2008, tensions resurfaced as Cambodia sought Unesco recognition of Preah Vihear as a World Heritage site.

The Thai Government of then-Prime Minister Samak Sundaravej, mired in a growing domestic political crisis, initially supported the Cambodian application.

The opposition accused the Government of selling out Thai interests, and the Government withdrew.

Unesco approved Cambodia’s application in July 2008.

As both sides of Thailand’s political divide sought to capitalise on growing nationalist sentiment, the Thai Government deployed troops near the temple (Cambodia said they entered its territory; Thailand said they did not).

Cambodia responded in kind, resulting in a military build-up along the border.

Fighting broke out in February 2011; each side accused the other of starting the conflict. After eight days and at least 16 deaths, Cambodia and Thailand agreed to a ceasefire, but sections of the border remain disputed territory.

What led to the current conflict?

The border dispute this month is not directly related to Preah Vihear, but it has been fuelled by the spiralling nationalism that shaped earlier conflicts.

A Cambodian soldier was killed in unclear circumstances during a border skirmish in May.

Thai Prime Minister Paetongtarn Shinawatra called Hun Sen, Cambodia’s de facto leader, to de-escalate tensions.

It had the opposite effect. In a recording of the call posted online by Hun, the Thai leader appears to speak deferentially to the Cambodian authoritarian, calling him “uncle”. Its release stoked outrage.

Once more, a Thai Government was accused of favouring Cambodian interests over Thailand’s.

On July 1, amid growing calls for Shinawatra to resign, the Thai constitutional court suspended the Prime Minister from duty.

On Wednesday, a land mine on the border wounded five Thai soldiers; one lost a leg.

Thailand recalled its ambassador to Cambodia, and the warplanes soon began dropping bombs.