As an American I don't mind helping other nations.... but this is a world problem. I don't think 'we' ante up until the rest of the world does as well. We aren't the world's police. Unless other nations want to start paying for our military.
The problem is the UN is a joke because the security council has nation(s) on it that will never do the right thing. It was a joke to begin with and is a joke now. So the UN won't send in a peacekeeping force, not that it would do by good even if they did as the Rwanda situation taught us.
And Ukraine isn't in NATO because of at least one country objecting, so they can't help either.
So we either wait on the sidelines until Russia likely takes over and proceeds to invade the other nations that joined NATO since 1997 and China sees our hesitation and invades Taiwan or we do something about it right now.
Either way, the world will blame the USA as usual. We either do too much or too little.
I wish we could go back to an isolationist way, but so many countries don't spend enough money on their defense due to expecting us to deal with their problems. If we sit this out it won't be long before China swallows up most of Asia, Russia does the same to Europe, and Iran and the other Muslim extremist countries try unsuccessfully to wipe out Israel.