That's a very good question for Putin, try asking it and enjoy gulag or sudden inexplicable death/disappearance.
What the fuck gives one state (Russia) right to dictate what sovereign countries do and don't do? I get this cold war mentality, it was the heyday of Russia, moving pawns, fighting wars, being global badass with some serious respect unlike now, doing whatever they wanted. That's over for 30 years, and the only one to blame is Russians themselves, and their fucked up mentality. But Putin would like some 21st century version of the same.
In same way I hated US for the invasion of Iraq based on pure lies, which were clearly lies to everybody I knew even when Bush jr was presenting them in UN (remember the US senators' cries about changing 'french fries' to 'freedom fries' when France and Germany refused to support this bullshit? Look where it led Iraq and surrounding countries. Not even going into topic of Afghanistan).
I come from eastern Europe. We were invaded overnight by russian (and V4, but mostly russian) troops in 1968 for the great sin of wanting to live in freedom from communist terror of previous decades. Just like Hungarians a decade before. This ain't something to forget. Even if I wasn't alive back then, my parents were and its very good to listen to elders in such cases, they have good stories to tell, lessons to learn. Hard earned lessons of oppressed lives which could never reach their potentials.