But I wonder, what pragmatic reasons might there be for Poland and Baltics to be equally vocal against Russia? Fear of Russian imperialism and attack is what I've read about so far, but I don't think that this is entirely objective, given that Russia right now has absolutely no imperial ambitions whatsoever, rather it is trying to fight the USA's influence extending into Ukraine. So such fears are understandable, yes, but not perfectly rational.
That's actually exactly it, and after the situation in Ukraine, the Baltic fears in particular are in fact set in two major, very recent, very extant precedents - Crimea and the Donetsk Basin. All three Baltics states have significant Russian minorities which could be used as catspaws in any potential crisis. In September, FSB agents
apparently entered Estonia and kidnapped Eston Kohver, an act openly revealed once he was secure in Russian custody by parading him for the televised media, and done two days after Obama's visit to Estonia and the reinforcement of NATO troops in Poland; he remains in Russian custody, where they plan to try him for espionage. Russia has also asked Lithuania for assistance in resuming prosecutions against Lithuanian draft dodgers who violated Soviet law before the fall of that state, an act Lithuania declined; while this is purely my speculation and only just over one month old, Lithuania is also the home of a brand spanking new LNG terminal supplying Norwegian gas for cheaper than Russia presently offers, essentially undercutting the Nordstream (reference also all of the political brouha surrounding that from the Baltic states, so the antipathy is mutual), adding a minor economic dimension. Latvia, in turn, has also alleged that Russian agents are working to support Russophone organizations in their nation, actively fomenting unrest, though I mention it last and least because there is little actual evidence for such assertions beyond Russian money going to pro-Russian groups (which is perfectly legal). Russian rhetoric has also escalated against the three nations, using language and forms rather similar to that used against Kyiv.
To digress briefly on this topic, Estonian and Latvian treatment of the Russian minority in their nations has been for some time been questioned, especially by Moscow, but also by independent parties such as Amnesty International. It isn't on the scale of systemized or tremendous legal oppression, but primarily due to the resumption of pre-annexation citizenship laws in these nations, which does not recognize the (de facto, albeit not de jure) Russification of these nations over the 51 years between annexation and independence and thus effectively alienated these people. Both nations require these stateless persons to take a language test in order to gain citizenship, an act decried as unfair. In recent years, there have also been moves in Estonia and Latvia to mandate education in their national languages, which has drawn significant protest from Russophones, especially in Latvia. That said, however, it is feared that just as Russia took advantage of unrest in Crimea to send in "polite men," they may choose to disregard or underestimate NATO and send similar active military provocateurs into the Baltic states in a
coup de main, especially in light of Russian rhetoric since Crimea. While NATO is highly unlikely to simply stand idly by as three member states are annexed, that is not something that the Baltic states can blithely assume Russia believes, and as such, they've maintained their staunch opposition in order to prevent a similar take-over in their own nation by demonstrating solidly that NATO and the EU will not permit salami tactics in the eastern frontier - a NATO firmly opposed to Russia, as opposed to wavering, is one that will serve as a deterrent and convince Russia that the Baltic states will not be as easily consumed as Crimea was.
Poland has far fewer Russians in their territory, but memories of Russian domination, in one form or another, for centuries (excluding the all-too-brief interwar period) since the Partitions have a significant political resonance domestically, and Poland has since 1991 cultivated good relations with Ukraine; Poland, like Sweden, was the chief advocate of closer relations between Kyiv and Brussels. In this case, I do not believe there is as direct an immediate threat (such would wait until the Baltic states have been secured if one assumes the worst of Russia, and a systemic, well-reasoned policy of gradual encroachment), but the capability exists in Russia, and many elements of strategic planning involve not only accounting for what may be done, but what can be done in a worst-case scenario where Russian ambitions are not limited, but in fact an attempt to resume hegemonic influence over their historical dominion for the last few centuries. In fact, Polish opposition to Russian moves has taken place in significant part against their economic interests (witness the vast losses in Polish agriculture due to the recent counter-sanctions) precisely because they believe their security interests are an overriding factor in the political calculus. Polish fears are also partially rooted in the popularity of several of Dugin's theories (especially his concepts on the systematic marginalization of Europe, including securing a "special status" for Poland) and the 2009 military manoeuvres during West-09 (including the simulated use of tactical nuclear weapons against Poland). In other words, Polish aims are also to ensure their own security from Russia; this is why they offered to host the US missile shield in 2007, and why they oppose Russian military interventions in Ukraine. So long as Russian involvement in Ukraine was limited to economic and political machinations around pro-Russian elements like Yanukovich versus pro-West elements like Yushchenko and Tymoshenko, Poland likewise limited their involvement in that manner; the second Russia changed the rules of engagement in Ukraine is the second Poland likewise requested NATO consultations and pressed for active sanctions, replacing the previous policies of economic engagement Prime Minister Tusk rather favored.