Contrary to what some people believe US gets involved in conflicts beneficial to US. US and Russia have been in a proxy war for years now. Russia was putting bounties on US military.

It is in US interest that Ukraine does as much damage as possible to Russia. Now, the world is seeing how weak the Russian military is, a lot of poorly maintained equipment. Sanctions are going to cripple Russian economy. The western world is completely turning against Russia. London is passing laws to stop Russian oligarchs from owning property. Switzerland stopped being neutral and is freezing accounts. This is unprecedented.

We might be witnessing the downfall of Russian empire.