Apparently it never worked properly (from https://www.tandfonline.com/doi/abs/10.1080/09636412.2017.1331639 https://www.tandfonline.com/doi/abs/10.1080/09636412

Apparently it never worked properly (from https://www.tandfonline.com/doi/abs/10.1080/09636412.2017.1331639 https://www.tandfonline.com/doi/abs/10.1080/09636412.2017.13...): > Meanwhile, the top Soviet EW warning commanders called OTH radar “virtually useless.”[88] Danilevich agreed, arguing that LUA was impossible before the development of satellites: “there were only above-the-horizon systems; there were no over-the-horizon systems ... These systems were not sufficiently reliable. They did not allow the reliable detection of launches. The only way to reliably determine the beginning of an attack is through human intelligence, but it is dubious that such data could be obtained.”[89] Apparently OTH radar operators would consult public reports about planned NASA space launches and then claim that they had tracked a launch on the appropriate day. But the ruse became obvious when weather delayed a launch.[90] [88] Fischer, “The Soviet–American War Scare of the 1980s,” 502. [89] Hines interview with Col. Gen. Danilevich, 24 September 1992, in Hines, Mishulovich, and Shull, “Soviet Intentions 1965–1985, Vol. II”, 41. [90] Bruce G. Blair, The Logic of Accidental Nuclear War (Washington, DC: Brookings Institution Press, 1993), 205.