Kaliningrad as warm water port is a myth. It freezes in winter (at least until recently it did).
I was a little surprised by this, since plenty of reputable sources characterize Kaliningrad as a warm water port. However, I see that George Kennan wrote in his memoirs "This statement, implying that Russia needed Konigsberg as an ice-free port, made no sense whatsoever. Russia already possessed on the Baltic Sea (assuming that one was prepared to concede the legitimacy of her possession of the Baltic countries, and no one, at Potsdam, seemed disposed seriously to challenge it) three perfectly good ports that were substantially ice-free: the former Windau (now Ventspils), Libau (now Lipaja), and Baltic Port (now Baltiyskiy) [I think Kennan means this:
https://en.wikipedia.org/wiki/Paldiski]. Konigsberg, on the other hand, lies forty-nine kilometers from the open sea, at the end of an artificial canal which is frozen several months of the year and has to be kept open, if it is to be kept open at all, by icebreakers. Konigsberg is, furthermore, accessible only to moderate-sited vessels, with a draft not exceeding about twenty-five feet. In both of these respects its qualities are not materially different from those of the major port of Riga, which had already fallen to the Soviet Union through its conquest and annexation of the Baltic countries. Thus it was true neither that Russia lacked ice-free ports on the Baltic nor that Konigsberg would have filled such a need had it existed. Yet Stalin's statements on this subject went unchallenged, so far as 1 can ascertain, at all the war-time conferences: and Mr. Truman made himself a party to the absurdity by solemnly informing the American public, in his personal report on the conference, that he had agreed to satisfy the age-old Russian yearning for an ice-free port." (I suppose one can argue that Stalin wanted a new Baltic port specifically to be part of the RSFSR just in case the Baltic states might again separate themselves from the USSR but that seems fairly far-fetched as of 1945.)