The other choice was to just let Russia deal with Ukraine with no intervention from the west.......we tried something similar to that last century and we all know how that turned out. Had the GOP not played politics with the Ukraine aid , they would have been in a much stronger position. As it is, they still holding their own. Ukraine is never going to "defeat" Russia, but their goal is too make it not worth it to Russia to continue.
The Japanese felt very optimistic about war with the US in 1941 at least in part because they saw us sit back and do nothing as our closest ally was fighting for their very existence against Germany and a poll taken in November 1941 showed 93% of Americans against entering the war, the Japanese thought they had a year or so to get as many quick bloody victories as they could and then the US would beg for peace and they would be able to negotiate and keep some , if not all of what they had taken. I bring this up because I believe had we not done anything, China would have already gone into Taiwan and possibly North Korea in the South Korea.
Ukraine is just now getting F-16s, and although they will be the best aircraft in theater, their effectiveness on the battle field has been curtailed somewhat because it took so long to get them to the Ukrainians.
The China / Russian agreement is more symbolic than anything, the Chinese economy depends much more on the US than it does Russia, and its already on shaky ground, Xi is not going to go too far out on a limb for someone like Putin and Russia