How'd you almost loose an entire armored corps to the Soviets in Manchuria?
Because I was stupid.
More to the point, I had an armored corps on the border and pushed towards Vladivostok when the war with the Soviets started. I had a number of other divisions in Manchukuo as well, so I thought I could just push out ahead and crush weak Soviet opposition (it was 1941, and I knew their officer ratio was crap compared to mine). I tried to do an encirclement of the city with the armored divisions like I'm running the first stage of Barbarossa. Next thing I know, the divisions are all out of fuel and supply, and strung out all over the place. One and two provinces into the Soviet Union, and the supply network collapsed under the strain. I barely extracted the forces in question, withdrew into Manchukuo, and licked my wounds.
Which is why I never run ART, ARM, LARM, AA, AT, or anything self-propelled in that theater anymore for offensive operations (I will stick INF/ART formations or maybe a single ARM division in key cities to defend).
I did something similar as the Soviets one time as well. I forgot that just because I had increased infrastructure on my side of the border, that didn't mean anything once I pushed into Manchukuo and Korea. Watched as some MOT divisions floundered and failed due to my hubris.