Doi Tung is a mountain located on one of the northernmost sections of the Thai/Myanmar border. At the top of a very steep climb lies a fortified hilltop viewpoint used by the Thai Royal Army to keep an eye on suspicious activities on the Myanmar side.
War-like as this outpost looks, its purpose is not so much to deter military attacks from Myanmar forces, but to prevent drug smuggling. Nowadays, these illegal activities are rare, but in the 1990s they were a contentious issue between the two countries.
From the Doi Tung outpost, you can see the deep trenches dug by the Thai Army along this section of the border. They are well kept and regularly used for drills. At the fort, there are barracks that house a small contingent of soldiers, who will carry on with their daily duties but will be glad to answer any questions visitors may have. There are also turrets and a memorial.
There are good reasons for this place to be a smuggling hotspot. First, on both sides, it is far from any major settlements, and it is sparsely populated. Second, it has no morphological barrier; the slopes of the mountains simply meet at the top, but apart from manmade fences, there are no natural obstacles between Thailand and Myanmar.
Due to the elevation, weather can be unpredictable. On a clear day, you can see an expansive view of the Myanmar countryside from the viewpoint, including a couple of mud huts at a distance. On a rainy day, the site acquires a ghostly atmosphere.