It's not true at all that E European states have had reason to fear Russia, going back centuries.
Hardly any E European states as we now know them existed a few centuries ago.
There were parcels of territory which were part of various different empires or ambitious kingdoms such as Austria-Hungary, Prussia, Lithuania - and even Sweden got in on the game.
Cities like current day L'viv have been known by several different names over the centuries, and populations have moved around, lock, stock and barrel as political fortunes waxed and waned and as their neighbours appeared with pitchforks and torches to speed them on their way. L'viv was a Polish city at the start of the last century, and known as Lwow. Before that it was Lemberg, the major city of Austrian Galicia. The countryside of the former Galicia is dotted with the ruined remains of Catholic churches and cemetries beating witness to the Polish Catholic - and Jewish - life that existed for centuries there.
In response to the devastation accompanying Napoleon and French secularism, republicanism, liberty, equality, and fraternity, Russia, Austria-Hungary, and Prussia formed the Holy Alliance around the time of the Congress of Vienna, which itself sought to produce a lasting settlement of European boundaries after the old European world had been destroyed by Napoleon. The French burned Moscow, and the Germans came close two centuries later.
Russia has been invaded several times over the centuries, disastrously, from east and west, and after each time has sought to make sure it will never happen again.