China is fully well aware that a naval blockade including Oil is a consideration of the US, especially some of the crazier elements that wants it brought to heel.
China saw what happened in 1930's with Imperial Japan with a US blockade so it knows its history.
Economic threat, followed by continued warships on its door step and open threats and after a while they assume a war footing. Looking at US tactics since WW2 they know that any treaty can be just ripped up by US when it suits it or just not ratified by Congress.
The real danger is escalation.
https://digital-commons.usnwc.edu/nw.../vol71/iss2/6/
https://www.reuters.com/article/us-c...-idUSKCN1S6140