Covert sites of the Laotian Civil War Wikipedia
Covert sites of the Laotian Civil War were clandestine U.S. military installations for conducting covert paramilitary and combat operations in the Kingdom of Laos. Airstrips within the Kingdom of Laos were originally designated by Air America as "Site XX" (with XX being a number). In September 1961, the designation changed to "VS XX", meaning "Victor Site XX". On 16 May 1964, the airstrips received their final designation; the site names then used the abbreviation "LS"—Lima Site—for unimproved strips, or "L"—Lima—for paved runways. The terms "Victor" and "Lima" were taken from the existing military phonetic code.
These sites typically were centered on a dirt landing strip for STOL aircraft such as the Air America Helio Courier or Pilatus Porter. These strips were often carved out along ridge lines, and were seldom flat, straight, or of sufficient length. However, they were crucial for resupply and personnel transport, including medical evacuations. To quote one source: "Some of these defied all the safety rules even of military aviation." A U.S. Air Force inspection team noted that even the best of the Lima strips was inferior to any air strips in Vietnam. Listing follows.