Excuse me? What?
Deterrence maintains peace because our nuclear weapons make an escalating war suicidal. As Secretary of Defense Robert McNamara laid out in his 1967 speech, deterrence is the “highly reliable ability to inflict unacceptable damage upon any single aggressor... even after absorbing a surprise first strike.”
The assertion that more military units are needed in Europe implies that America’s nuclear deterrence is insufficient to do the job on its own. There are only two reasons why this might be the case. The first is that America has incorrectly signaled to Russia that nuclear weapons will not defend the Baltics. The second, is that President Trump’s transactional mindset and past musings on not upholding mutual defense obligations are serious and have signaled to Russia Trump’s ambivalence towards NATO. ...
America should focus on signaling deterrence without putting Russia in a corner. The idea that more boots are somehow necessary on top of 1,350 deployed nuclear warheads aimed at Russia’s cities is absurd. If over a thousand nuclear missiles cannot signal to Russia that an incursion into NATO territory is a bad idea, then any additional soldiers never will. [emphasis added]
Have we forgotten everything we learned during the Cold War about nuclear deterrence?
McNamara's explanation in the above excerpt is about why a Soviet nuclear surprise first strike would be futile. America would absolutely have enough surviving nukes and the obvious willingness to respond with everything we had to destroy the USSR in response.
Taking that deterrence and applying it straight to non-nuclear attacks is plain wrong. Indeed, let me quote from a post that criticized an author's claim that nuclear weapons are worthless to deter attacks on NATO:
I don't believe that anybody since the early 1950s claimed that the threat of nuclear weapons would deter conventional attack on even a member of NATO. That deterrence required absolute nuclear monopoly on our part to make.
It is simply not credible to believe that nuclear retaliation is a believable threat in the face of a subliminal invasion such as Russia carried out in Crimea.
Nukes deter use of nukes. This allows the fight to remain at the conventional level. Saying that nukes wouldn't deter a Russian conquest of the Baltic states also means that Russian nukes wouldn't deter a NATO counter-attack to liberate them--or to capture Russia's Kaliningrad enclave as a bargaining chip.
Nukes deter conventional advances that threaten a very vital national interest. Their main deterrent value is the uncertainty of what might trigger such a calculation to use nuclear weapons and the general fear that any conflict could escalate to nuclear warfare despite nobody wanting to use nukes.
So yeah, we need the ability to fight for the Baltic states using conventional arms. Although I wouldn't deploy enough troops to defend and hold the Baltic states because enough to do that would be an actual NATO threat to the important city of St. Petersburg; and that concentration of NATO troops would invite the Russians to advance through Belarus to cut off the NATO army in the Baltic states.
People really need to brush up on Cold War nuclear deterrence theory and practice.
