I believe Putin knew about the planned incursion in advance and allowed it to happen. He redeployed a Chechen force, skilled at ambushes, from fighting in the Ukraine to an area in Russia near the border in advance of the incursion. The bulk of the Ukrainian forces are strung out on or near the border while much smaller raiding parties travel inward to push as far as possible, through dense forests, where they are ambushed.
Putin could have closed the border but he let thousands of Ukrainians cross in. I doubt any of the Ukrainian forces, and their foreign mercenaries, will be permitted to return home, ever. 15,000 of Ukraine's troops went into Russia/ Since Putin has said their actions are not military, but are terrorism (i.e., shooting at citizens, attempting to damage nuclear power plant etc), he says the Geneva convention rules do not apply. That's why all but the Chechen group are not military. They may add some military troops along the way, but the Russian forces have been militias for the most part.
In the General/Chat forum, on a thread titled Ukraine's Kursk Offensive: The lessons and risks of Ukraine's push into Russia , McGruff wrote: Current analysis of Ukraine’s offensive into Russia.
https://x.com/BowesChay/status/1825267668137513421
