The things is, sanctions have historically been very effective at harming the countries being sanctioned - but now that China makes all of our shit and have the confidence in their foreign policy not to abide by US-lead sanctions their effectiveness is a lot more questionable.

Even still, I would hesitate to call sanctions totally useless from the US’ perspective - at least for countries that aren’t physically close to China, like Iran, Venezuela, and Cuba, they still have a big impact. Hopefully that continues to change as the BRI continues to build out.

edit: Here’s a cursed thought - we’re going to have another Cuban Missile Crisis, but there won’t be any missiles and it will actually be because China wants to expand a port.