[4][6] A pillar was erected indicating the border alignment in this section, and a demilitarised neutral zone set along the frontier.

[6] A Chinese-Korean boundary team surveyed the Mt Paektu area in 1885–87, however there were disputes over whether the pillar had been moved, and the two sides were unable to agree precisely which of the several headwater streams should form the frontier.

Chairman Mao and the Communist Party (CPC) assumed rule over China after it won the Chinese Civil War, following the Liberation of Beijing by the PLA in 1949.

In 1962, North Korea and China signed a border treaty in secret which fixed the boundary line along the Yalu and Tumen rivers, with the middle overland section running across Mount Paektu and through Heaven Lake.

International calls are strictly forbidden in North Korea, and violators put themselves at considerable peril to acquire such phones.

[19] Chinese authorities began building wire fences "on major defection routes along the Tumen River" in 2003.

[20] Beginning in September 2006,[20] China erected a 20-kilometre (12 mi) fence on the border near Dandong, along stretches of the Yalu River delta with lower banks and narrower width.

[21] In the same year, it was reported that North Korea had started building a fence along a 10 kilometres (6.2 mi) stretch of its side of the Yalu River, and had also built a road to guard the area.

[28] In 2015, a photojournalist who traveled along the Chinese side of the border commented that fencing was rare and that it would be easy to cross the Amnok river when it was frozen.

[31] Rumours of Chinese troop mobilizations on the border frequently circulate in times of heightened tension on the Korean peninsula.

[33][34] This was apparently in preparation for a large influx of North Korean refugees if the Kim regime collapsed in a potential conflict with the United States.

By August 2020, the regime had established a 1–2 kilometer buffer zone in front of the border where official permits were required to enter; trespassers would be "fired at without warning".

[36][37] In May 2023, newly constructed double walls and guard posts were observed along hundreds of kilometers of the border, according to satellite photos published by Reuters.