As Russia's intervention in Ukraine is increasing, the main focus of some news is how many troops are ready for invasion:
Military units heading into Ukraine will be drawn from up to 190,000
personnel gathered close to Ukraine's borders in recent months.
They are equipped with everything from tanks and artillery to air
power and naval support.
In such a context I expect that NATO prepares a similar (the same order of magnitude) number of troops and equipment on its Eastern flank (The Readiness Action Plan). This article suggests 40K as the number of troops:
(..) A significantly enlarged Response Force of 40,000 troops
It is not clear how many troops NATO has on its Eastern flank. I am interested in a very rough estimate, as this will most likely change in the near future.