In the military action against Vietnam in the late 1970s, the People's Liberation Army dug a large number of so-called "cat ear holes" (猫耳洞). A cat ear hole, a more or less horizontal foxhole, refers to a hole in the side wall of a trench or soil slope that can be used for shelter. The entrance should be open on the sunny slope and leeward place with good soil quality. Cat ear holes are well-insulated and the temperature inside the cave is usually about 12-20°C higher than outside of the cave.

The name cat ear hole was created by the Chinese themselves. China has a long history of using cat's ear holes. They were used extensively in the mountain wars in Guangxi and Hunan during the Anti-Japanese War.

Link:

Xifu Zhao Wangye (西府赵王爷), "猫耳洞，对越反击战中最特殊的存在，让士兵又爱又恨" (Cat ear holes, the most special spots in the counterattack against Vietnam that soldiers loved and hated), Sohu.com, 10 June 2020