Khao Phra Wihan National Park is a protected natural area in Sisaket Province, Thailand, that contains numerous ruins of the 11th century Khmer Empire. The park lies 98 km (61 mi) south of the town of Sisaket, at the end of Thai highway 221. Sited on a red stone cliff that is part of the Dangrek mountain range on the southern edge of the Khorat Plateau, it abuts the international border between Thailand's Sisaket Province and Cambodia's Preah Vihear Province. The name of the cliff in the Royal Thai General System of Transcription is Pha Mo I Daeng.
The park atop Pha Mo I Daeng is the Thai gateway to ruins associated with the temple of Prasat Preah Vihear, and was generally open to everyone upon payment of entrance fees. When relations between the two countries were normal, the temple ruins were also accessible from the Thai side. Both sides charged additional entrance fees for such access, but Cambodia did not require visas. Access from the Cambodian side was to the temple ruins only. The International Court of Justice awarded the temple ruins to Cambodia in 1962, but these are located in an area of 4.6 km² that Thailand still claims. Nevertheless, in 2008 the World Heritage Committee's 32nd Session listed the Temple of Preah Vihear as a UNESCO World Heritage Site, which prompted an armed dispute.
In 2007, Cambodia proposed to the World Heritage Committee's Thirty-First Session that Preah Vihear Sanctuary be listed as a UNESCO World Heritage Site. As Cambodia and Thailand had not resolved border issues concerning the site, the Committee postponed consideration to its 32nd session, and asked Cambodia to provide a complete management plan for the area. Early in January 2008, Cambodia invited Thai experts to participate in a site survey of the Buffer Zone, and then to Siem Reap and Phnom Penh to collaborate with a team of international experts in the making of a plan for the area in Cambodian territory. Thai experts found "unacceptable scientific inaccuracies" in documents presented, dissociating themselves from the group, and then published in rebuttal their own Management Plan for Preah Vihear Mountain and its Setting. A PDF English language version of the Plan was released.
Following a February 2011 request from Cambodia for Thai military forces to be ordered out of the area, judges of the International Court by a vote of 11–5 ordered that both countries immediately withdraw their military forces, and further imposed restrictions on their police forces. The court said its ruling would not prejudice any final ruling on where the border in the area between Thailand and Cambodia should fall. It could take the court many months or even years to reach that decision. Abhisit Vejjajiva (at the time caretaker Prime Minister since the 2011 Thai general election) said that Thai soldiers will not pull out from the disputed area until the military of both countries agree on the mutual withdrawal. "It depends on the two sides to come together and talk," he said, suggesting that an existing joint border committee would be the appropriate place to plan a coordinated pullback. At the present time (June 2019) there has been no resolution of the border dispute and the Thai military still occupy Pha Mo I Daeng overlooking the sanctuary. Needless to say there is not access from the Thai side.

Source: https://en.wikipedia.org/wiki/Khao_Phra_Wihan_National_Park