Literally everyone in the 90s and 00s: "NATO expansion towards Russia will lead to violent escalation, don't do it."

US: Does it anyway. Also dismisses several Russian initiatives to Join NATO or at least setting up a free trade zone from Lisbon to Vladiwostok.

Russia: Outright tells the US trying to get Ukraine into NATO was its red line.

US: Coups the Ukrainian government, puts nazis in government and swarms the country with agents.

Ukraine: Starts supressing its Russian minority, worshipping nazis. Starts a civil war.

8 years, and several peace initiatives by Russia later: Russia intervenes int he civil war citing "responsibility to protect", which the US previously used to bomb Yugoslawia and cut off Kosovo.

You: "RUSSIA IS A PROBLEM!!!1111111"

Yeah, because it didn't roll over and let the US fuck it again.