Since 2014, SOCEUR has had forces working with allies in the Baltics to help bolster local militaries. With no end in sight to a broader U.S. military campaign to reinforce NATO’s eastern flank, officials said there was a need for upgrades for the special operators. The facilities, which serve as a small base of operations in Baltics, are on an undisclosed Estonian military site.
Special Operations Command Europe working with local militaries and militias will help with low-level enemy operations. But an invasion by Russia won't be stopped in Estonia, Latvia, or northern Lithuania--at best.
But for that case, I assume that the special forces (as well as other NATO special forces) are also preparing for stay-behind operations should the Russians overrun NATO's Baltic states.
I've noted that mission since the Russian invasion of Ukraine that started with the Crimea take-over.
The Navy and Air Force will need to support these special forces and the Estonians, Latvians, and Lithuanians who resist the Russian occupation until a NATO counter-offensive can liberate them.
UPDATE: And obviously, the better NATO can carry out these missions, the less Russia will believe they can get away with a rapid smash and grab.