@mammal The DPRK nuclear capability is based on one test shot, regarded to have been a partial yield (a “squib” shot, or failure). Their medium-range missile tests either failed shortly after launch or were wildly inaccurate. It’s questionable whether their nuclear “warheads” can even be mated to those missiles. Kim’s rhetoric has about the same value as Saddam Hussein promising the “mother of all battles” in 1990. DPRK only has the physical capability to invade the ROK; this would be a classic “quantity vs quality” battle. Unlike the Soviet Union of the 40s and China of the 50s, Kim does not have limitless reserves of cannon fodder to throw away. In any event, the PRC is his meal ticket and won’t permit him to start such a war.
As to the historicity of communist armies success, the only major wins were the USSR in WW2 (after almost losing) and the Chinese Civil War. The Korean War was a draw, the Vietnam War was a forfeit. As for losses; Eastern Front in WW1, war with Poland in the early 20s, the tiny Finnish army massacre or capture of a million Red Army troops in 1939–40, the failure of communist arms in Malaysia, Indonesia and Thailand, and the miserable attempt to hold Afghanistan after the 1979 invasion (the USSRs “Vietnam”). China is no longer a communist state, merely a totalitarian oligarchy using the label. The DPRK is a family dynasty “tributary state” of China; a tiny ruling class and 18,000,000 undernourished slaves doing exactly what they’re told, no more, no less (a house of cards waiting to collapse).