Responding to Russian Exercise Zapad 2017 - concerns and strategy

The US Air Force sent seven F-15C Eagle fighter jets to Siauliai Air Base,Lithuania this week in advance of Russian military exercise Zapad 2017,or West 2017 in English.That's three more than typical for the US rotation in NATO's Baltic Air Policing mission,securing the air space for the Baltic states,which lack significant air power.
Zapad runs from 14-20 September.It is held every four years,so is not in response to specific geopolitical events.Nonetheless,it is jangling nerves in the Baltic states and Poland on NATO's Eastern Flank,who are so close to the drills, which are being held in Belarus,Western Russia,Kaliningrad and the Baltic Sea.
Besides the F-15s,the US is deploying 600 extra airborne troops in the Baltics during the exercise.So it is reacting in a fairly restrained manner to Zapad,signaling concern but not alarm,and not giving Russia any excuse to overreact.*
Russia denies there is anything to worry about;they are just staging defensive exercises with Belarus.Should NATO be concerned at all?Consider the thoughts of US Army Europe commander Lieutenant General Ben Hodges,which he expressed to Reuters:
When Russia went into Crimea,that was against the backdrop of an exercise.When they went into Georgia-that was an exercise.Their history is full of examples where they don't live up to any treaties...They routinely violate those things.
We are all working hard to be at the highest level of readiness during an exercise like this.*
Russia says it and Belarus are only sending 13,000 troops to Zapad,along with 70 aircraft and 700 pieces of equipment,including tanks and artillery.Most interesting in the tank realm is the reconstituted First Guards Tank Army-a force of 500-800 tanks plus rocket artillery that is clearly of an offensive orientation and will be a showpiece of Zapad.It participated in the Soviet invasion of Czechoslovakia in 1968.
NATO believes the real number of troops and civilian participants could exceed 100,000.*
The 2013 iteration of Zapad ended with a simulated nuclear strike on Warsaw,Poland-hardly a reassuring memory.And NATO observers have not been invited to the drills as of yet-another reason for keeping an eye out for an unpleasant surprise left behind when Zapad comes to an end.