Pact and Pressed

"I wanna know why you're pressin' me."
--Latrell Walker (Exit Wounds)

Map shows what NATO expansion has meant over the past 30 yrs. Not only is the space between Russia and 'the West' becoming smaller, but many of the expansion members were formerly Warsaw Pact countries. 

The Warsaw Pact was system of shared security created in 1955 as a reaction to West Germany joining NATO. It can be seen as another expression of the Cold War pitting the two superpowers. The US led NATO, and the Soviet Union led the Warsaw Pact.

Unlike the Warsaw Pact, which dissolved when the Cold War ended, NATO persisted and, in fact, began scooping up former Pact members. Today, Belarus and Ukraine serve as the primary land buffers between the NATO collective and Russia.

It is straightforward to see how this situation has left Russia feeling increasingly pressed. Now it is acting to relieve that pressure.

Again, imagine a similar situation occurring domestically, with country members of a CCP-led shared security collective surrounding the US.

How would the US respond?