"Moscow is ready to use its arsenal to deter pushback against its aggressions. NATO needs a plan for how to stare down such threats.
"In a contest over the Baltics, for instance, Moscow might seek to use its “little green men” and its advantages in conventional weaponry in the immediate area to create a fait accompli in, for instance, eastern Estonia. Having bitten off a chunk of NATO territory, Moscow might then state that any NATO attacks on Russian sovereign territory would constitute unprovoked escalation and threaten a nuclear response should NATO respond.
In such a scenario, the Russian air defense and other military systems that NATO would need to attack in order to dislodge Russian forces from Estonia could easily be operated from within Russia’s own territory. If unprepared, NATO might find itself unwilling to countenance precisely the kind of escalation it would need to undertake to eject Russian forces from the territory of a member state. A failure in such a contingency could precipitate the collapse of the alliance, with grave consequences for regional security and world order.
This scenario may sound a bit far-fetched, but it isn’t impossible.
The Kremlin wants to re-establish its sphere of influence in its near abroad, possibly including the Baltics, and it wants to push back and divide NATO. We know that Russia has the conventional capabilities to invade sovereign states and shift borders, as we have seen in Ukraine. Many Westerners today imagine the Russian military as the hobbled, drunken giant of the 1990s. In fact, at least a good chunk of Russian forces today are well-trained, well-equipped and professional.
Russia, moreover, has been giving a great deal of attention to its nuclear forces, including to how it can use these forces for practical strategic and political effect. The Kremlin has evinced particular interest in the notion of “escalating to de-escalate”—the idea of conducting a dramatic nuclear (or lapel-grabbing nonnuclear) attack to spook the other side into backing down...."
http://www.wsj.com/articles/nato-needs-a-nuclear-strategy-update-1432751143