They did, but after the Khalkin-Gol and Nonmomhan disasters and the involvment with the Sphere of Cooperation plus Pearl Harbour, they gave up on those plans.

Besides who cares for a barren desert where you see grass for only three months in a year? There was nothing in Siberia but empty vastness.*

What northenr resources? While there were the rich pickings of rice, oil, rubber, metals, etc in China and Southeast Asia, why go for snow and grass? Besides, as for what concerns North the already had Manchukuo and that was Northern enough for them.



* Quite the opposite but the Japanese did not know that, it was a closely guarded secret. And what there is is so spread apart the entire Siberia that it is simply impossible to control. Remember there was only one Transsiberian line, with a few branches for some specific places, but even those were secret. And when a in Stalin's time (and others) somebody said the word 'secret' says, then it meant 'damn top secret'!

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