Sudoplatov wrote his works decades after he was disgraced and kicked from the party. He was writing as a bitter man for sensationalism and self-aggrandizing. His memoir "special tasks" was sold to the west as this grand tell-all, only to quickly be rescinded by the US press like NYT after historians pointed out how sloppy it was and that no one had consulted other sources. He overstated his intelligence influence in the Manhattan Project, making it seem that many figures had been assisting him, and that the Soviet atomic bomb was the product of his intel, and not Soviet scientists.

https://www.washingtonpost.com/archive/local/1996/09/27/pavel-sudoplatov-89-dies/46d6e456-cf25-40e4-aeef-2b0e2f69b59b/

The FBI and SVR both heavily criticized the work.

Now the border conflicts are real. The north was controlled by the Republic of China which was backed by Japan, the KMT had tried and failed with the first Northern Expedition in 26-27. The Soviets had already dealt with Japanese invasions during the Civil War and threats made to their Mongolian People's Republic allies. In December of 1927 the Communist uprising in Guangzhou happened and was put down, causing the KMT to cut ties to the USSR. So come 1928 Japan, its allied government, white emigres, and the KMT all existed as threats in the region. The whites had a couple armored trains operating in the north as well which they used to fight the KMT, and in 1928 when the KMT won they captured a train and tortured the Russian mercenaries in a very public manner. The expedition also was a factor in Stalin and Trotsky's split, with Stalin wanting to support the KMT and have the CPC join them.

However it wasn't till 1929 that full border war began between China and the USSR, and the Soviets won that definitively, so clearly JAO going along in development was not solely to plug a gap. Though the Far Eastern Bureu did deport and imprison the Chinese population after this conflict and moved Siberians and Europeans in instead. Sort of a trial run for later deportations.

edit: wait are you being sarcastic? Obviously Im not claiming the only info on this comes from him, my point is wikipedia uncritically citing him and a statement that the "only" reasons something happened was pertaining to his field and work is suspect and not a good source. The existence of these events is not in dispute and you'd have to be very dense to think that was what anyone was implying. It is the validity of Sudoplatov's claim and its definitiveness that is in question.

Every source that is used belies a bias and constructs a narrative. Them using one from an untrustworthy guy that just so happens to simplify everything down to "Stalin didn't care about the Jews at all" IS telling. It is not adequate and needs to be given the caveat at the very least. Actually challenge wikipedia's choices of sources