Because Putin has been an aggressive imperialist all his life. His burning ambition is to reestablish the Russian empire.
Estonia, Latvia, Lithuania, Belarus, Moldova, Armenia, Azerbaijan, Georgia, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Ukraine, Uzbekistan, Poland, Alaska, Finland, and Romania.
All have Russian speaking minorities, all were once a part of the Russian empire, and all have a good reason to fear Russian Military mischief in the future unless the world contest Putin's Military expansionist desires. 1/6 of the worlds landmass once belonged to the Russian Empire. And that is what is really at stake without checking Putin's current mischief in Crimea.
Oh and when you add in China’s expansionist desires, you create a world economy where the US, is just another thrid world player. Your ability to buy goods and food will be NOTHING like the posterity your used to.
Poland has very few Russians.