Cambodia gained independence in 1953, and the two state since then have had a fractious relationship. A dispute arose in the late 1950s over the ownership of the Preah Vihear Temple, which lies adjacent to the border in the Dângrêk Mountains. In 1962 the case was referred to the International Court of Justice, which ruled in favour of Cambodia, however Thailand expressed reservations as to the outcome. The mid-1960s also saw a dispute over ownership of Ko Kut island. These disputes faded as Cambodia became engulfed in a series of conflicts in the following decades and the disastrous rule of the Khmer Rouge, with thousands of refugees crossing the border. By 1981, over 250,000 Cambodian and Vietnamese refugees lived in twenty camps along the border, supported by international aid agencies and the United Nations Border Relief Operation. Sporadic fighting broke out along the border following Vietnam's invasion of Cambodia in 1979, continuing throughout the 1980s until Vietnam withdrew from the country in 1989. In an effort to stop Khmer Rouge infiltration from Thailand, Cambodia built a large fortified fence along the border in the second half of the 1980s. Since the advent of peace in Cambodia in the early 1990s relations with Thailand have once again soured over the Preah Vihear issue, as well as, to a lesser extent, Ko Kut island. A border commission was set up in 1995 in an attempt to settle the issues peacefully, however it has made little progress and a full border demarcation satisfactory to both sides remain outstanding.