The new administration party line is that Putin is now weak and acting out of just that weakness by sending troops into Ukrainian territory — a sort of chihuahua who took on a pit bull because he knew he was weak.
But even weak states do not typically invade others because they accept that they are weak (and thereby expect to lose?), but usually because, even if weak, they at least still expect to be strong enough to win. Even demonstrably weak Mussolini apprised the political and military landscape and thought that he could win something when he opportunistically invaded a tottering France in June 1940.
Of course, the point is not so much whether Putin is acting out of weakness and frustration at Obama’s purported strength (a fantasy), or even whether he is acting out of strength due to Obama’s clear weakness (most likely), but rather that he is acting at all.
While he absorbs eastern Ukraine, we may call that gambit stupid, catered toward Russian public opinion, self-destructive, strategically inept, and proof of weakness. But those remain mere hypotheses until he withdraws, when we can be convinced that all such rationalizations in fact were accurate or, at least, accurate now though they were not so accurate at the time of his invasion.
In mid-1939, Hitler was weaker than France and Britain combined, but that did not stop him from invading seven countries in a row. He was even weaker than the Soviet Union when he foolishly invaded it in June 1941, and weaker than the U.S. when he stupidly declared war on us on December 11, 1941. But all those stupidities did not prove that Hitler at the time thought that he was weaker than his targets — or that he had good reason from recent history to accept that he was weaker. Even Neville Chamberlain did not claim that Hitler had invaded Poland because he was weaker than France and Britain (though again he probably was).
States invade others because they feel they can get away with it. If they fail, it is usually because they or their intended targets had originally miscalculated, some sort of hostilities ensue to correct those inaccurate initial appraisals, and peace follows when everyone again knows who was truly weak and who strong in the first place.
When Putin understands that we were and are strong all along and that he was and is always the weaker party, he will recede. And calm will return. And if he doesn’t leave Ukraine alone, then he was sort of right all along that despite our vastly superior economic and military power, we were sort of weak as he suspected.