I put the blame for what’s going on in Ukraine on both the US and Russia. They each use the country as a proxy against the other much like happened during the cold war rather than keep out of its affairs. The US trying to setup NATO on Russia’s doorstep, is sort of like the Russians trying to setup shop in Cuba. A neutral Ukraine that does trade with both countries and not militarily aligned with either would be best for Ukrainians IMO
As for China, the US wisely intervened in Taiwan during the cold war when Mao, an actually communist, was pushing communism. Today though although CCP call themselvses communist they aren’t really communists. Reforms since Mao’s passing has thoroughly put China in mixed economy camp (which is why their economy is poised to surpass the US). They also don’t export communism like the Soviets used to do and stick to their own borders other than shenanigans in south China sea in violation of UNCLOS.. I don’t think they would invade Taiwan unless provoked by recognition of Taiwan independence. In principle the US has agreed with one-China policy since Nixon. Most of China’s demographic is Hans Chinese. I think they would prefer a unified China themselves but the still authoritarian CCP has created a wedge. They don’t want to end up like Hong Kong after reunification. IMO a solution is to be found once China finally allows democratic multi-party elections. It will ease fears that Taiwanese leaders won’t be imprisoned for defending democracy. Could be awhile though.
The US also needs to understand that its economy is no longer going to be the biggest in the world for much longer. It shouldn’t let national ego for hegemony lead it into trade wars that will harm its own economy. Both India and China has spent considerable effort focusing on STEM. This is at the heart of any economy. In China’s case they not only far outnumber the US demographically but have 8 engineers employed for every American engineer. By the turn of the next century, China’s economy will likely be double or even triple the size of US economy. I would also not be surprised if even India has a substantially bigger economy than the US by then too.
As for Iran, the the US (and UK) does carry some moral responsibility for decades of oppressive totalitarian rule in Iran under the Shah (which was covertly put in place by operation Ajax). The US was on the right side of the cold war but sometimes inappropriately props up American friendly dictators in lew of democracy.. Nevertheless, Iran overreacted by putting theocratic basket cases in power rather than choosing democracy. It’s also over 40 years since the Shah was disposed. Until they put more moderate form of government in power rather than theocrats the Iranian government should not be trusted.