The Suwalki Corridor is a small, key land area for NATO that connects Poland and NATO-allied Europe with the Baltic states of Lithuania, Latvia, and Estonia. A Russian challenge to the area could cut off NATO access to these states and achieve a key Russian objective of undermining the NATO alliance. According to a former Lt. Gen., “The Kremlin wants ‘a seat at the high table and they do that by undermining the alliance…The way that they do that is show that the alliance can not protect one of its members, show that we are too slow, that we can’t deter that sort of attack. If you accept that premise, that they might do a limited attack to demonstrate that NATO cannot protect its members, that would create a problem.’”
Source: This is How Russia Could Test NATO, Warns Former US Army Europe Commander – Defense One