I believe this. Perhaps Stalin had figured it out, or perhaps he simply fell into a win-win situation. After adoption of George Kennan's "containment" strategy, the USA / Truman had drawn its "cordon sanitaire" to NOT include Korea. It is believed Stalin new this, so could tell Kim Il Sung to invade the South without fear of response. Once the US/Truman did, in fact, respond (due to fears of further aggression and political pressure), Stalin then had an active and organized Mao Tse-dong to make sure both sides bled themselves.
Of course Stalin would claim to another Communist vassal, after the fact, that he had it figured out all along....
Only....Stalin seriously dissed Mao Tse-tung on the latter’s official visit to Moscow where he kept the ChiCom leader waiting two hours outside his Kremlin office. Mao burned with resentment over this snub for as long as he lived. Ever afterward Red China was the USSR’s bitter rival for the title of “Mother of Revolutions” as Mao didn’t get along with Khrushchev, Kosygin, nor Brezhnev. What about the Ussuri River border clashes in 1969, nearly bringing the two communist powers to general war?
If Stalin so underestimated U.S. and Western resolve in the Korean Peninsula that he withdrew Soviet veto power in the Security Council just to draw an entire U.N. fighting force into the peninsula so they would get bogged down for years, then what was he thinking? The shooting stopped with an inconclusive ceasefire soon after his death, and little was gained as far as the world communist movement was concerned.
There’s often a tendency to ascribe to an enemy a wily cleverness that he may not actually possess. I think this to be the case here.
Stalin knew because Dean Acheson had said so publicly. Stalin probably also knew the state of American unpreparedness in 1950.
Truman had taken a meat ax to the defense budget and our military was in terrible condition. MacArthur had one full strength infantry regiment under his command - the segregated, all black, 25th Infantry. Unfortunately the 25th had the worse equipment in the army and was used as a dumping ground for incompetent white officers because the army thought blacks would not fight. Racism, both disparagement of blacks and underestimation of the Chinese cost us thousands of lives in that war.
The rest of MacArthur's command was under strength and out of shape from four years of garrison duty in Japan One example is the first US tanks to engage the North Koreans, M24 Chaffees. They fired one round and were disabled because they had no hydraulic oil for their recoil systems and their guns came off the trunnions and sort of rattled around inside the turrets. Seems Truman's pal defense secretary Luis Johnson had seen fit to cut recoil oil out of the budget. After the shooting started and money was no longer a problem MacArthur rounded up some old M4E8s that were rusting away on Guam and sent them to Japan where Mitsubishi was able to refurb them and send them into action.
The Truman administration had let our defensed down and Stalin made us pay. Stalin was probably justified in assuming the US wouldn't fight with an army in the shape it was in. He just underestimated the arrogance of MacArthur, the incompetence of Truman and the speed with which the US military was able to and mobilize and react.