And, of note, the US has not blockaded or otherwise physically interfered with Russia's ability to trade, so that they'd be willing to cross that line with China seems far fetched to me. — boethius
Truly?
I'm convinced the second conflict breaks out, all of China's sea trade will be cut off and that this is their main strategic challenge. This threat is what prompted them to launch the Belt & Road Initiative - to create overland alternatives to US-dominated sea lanes.
The threat is strategic in nature. That is to say, during peace-time all is well, but during war all of these trump cards would be played. And if you're China or Russia, and you see the US quietly collecting trump cards against you, they perceive that as a threat. It's essentially a knife aimed at their throat.
When the conflict finally happens it will be framed in such a way that China is the bad guy, and 'the West' will unquestioningly accept the American narrative as truth, as we saw in the Ukraine crisis.
I just don't see how the US could maintain such a blockade of any extended period of time. — boethius
Note that cutting off sea trade is different from a total blockade. The US and its Pacific allies don't need a total blockade, because they control several rings of islands and straits that would make it extremely easy to monitor and target Chinese sea traffic.
Crippling Chinese trade would be a walk in the park for the US. The Chinese know this, and it's also the reason why the Chinese are very careful to avoid armed conflict.
Personally, I think the US is gearing up to create a situation like this before the Chinese fully surpass the US. The problem for the US is that its pivot to Asia is taking time, due to unfinished business in Europe and the Middle-East. However, this is also looking a lot like "shaping the battlefield" - ensuring all pieces are in place before the grand finale starts.
Note that if there is chaos in Eastern Europe and Iran, China would be effectively cut off from Europe, the Middle-East and Africa over land.
These things aren't coincidental.
Many powerful people in the US, really, really, really wanted to go to war with Iran, but it's simply not practical to do. — boethius
There are many speculations about Raisi's death having been an assassination. If that's the case, it follows a familiar pattern of the US sowing chaos in the Middle-East.
Iran just so happens to be a crucial link in Chinese overland access to the rest of the world.