The NATO response force currently consists of approx 50K
This force consists of land, air, naval and spec ops assets. It is by nature a multi-national rapid deployment force under a single command structure (SACEUR).
This force is highly capable and trains constantly - in the event of a full scale war with Russia they would be able to deploy completely in 5-10days. Obviously NATO can then draw on the military resources of each member state to feed into theatre as it sees fit.
Given the current state of the Russian army the NRF would wipe the floor with Putin’s scruffs without the need for further backup.
300K



Raw conscripts, press-ganged Cubans and fat knackered criminals. Against a highly trained, professional force they’d get a right kicking.