Zero. Chinese can't even cross first island chain without being beaten black and blue by USA.
First of all I think the Chinese are smart enough to take the slow boiling approach than to initiate war as frankly it has been more cost efficient for them and also because they have time on their side.
America on the otherhand has only raw firepower on its side in terms of numbers and quality and even their numbers and quality edge they are losing with time as some of their recent naval acquisitions,future naval acquisitions in light of recession being the factor and Chinese naval buildup capability in terms of shipyards and workhorse ship designs and the numbers in which they are cranking out.
And another think that people here miss but is my forte is the cultural and societal factor.
I thinks the Chinese nationalistic aspirations put forth by the ccp(ironically) are more stable and palatable and desirable to the Chinese populace than the American aspirations in scs put forth by American governmen are to the American populace .First of all the goals of American government are usually not long term in this and are a mess as different factions have different ideological worldviews that are very different and sometimes incompatible and hence they do not translate to better and smooth work on the ground. The people of America are also divided on this from pacifism to apathy to militarism to isolationism, etc.
the ccp's goal of creeping expansion to gain territory and resources is not going to bother the average Chinese and could also be a source of pride considering the nationalism of the average contemporary Chinese person. it will only hurt if it has harsh material consequence in terms of war and treasure which is why China prefers the slow burn method and this has been very effective with many small countries. India is the only country this has not worked or been having low returns for obvious reasons.
The American populace are also culturally and demographically divided to a point it will act as an anchor for any future government to act calmly on the south China sea area as they will readily and willingly play spoil sport and might even aid the enemy. China on the other hand is strengthening it's core by extinguishing potential problematic ideologies and populations from which such ideologies could potentially come from such as Christians, Islam, uighers, Buddhism, Hong Kongers, etc through all possible methods for a long time consistently with all parts of state machinery working together and also preventing any internal or external backlash.
From what I see and I always tell it as it is I think all of it has been fairly successful and I think even though many YouTube channels will sing the praise of Hong Kong they will assimilated in due time with a whimper. This will give a solid Han core that will support the cup which has morphed into a nationalist party in recent decades with Maoist imagery worn as clothing.
In fact surprisingly I think the future threat from China will come from India rather than the west as we are also strengthening our core and acting as a civilisation rather than a landmass with tenants and a share price like most of the west. As people are more motivated by tribalistic tendencies of defending my land,family,my religion, etc rather than nebulous notions of sovereignity,universal values, Human Rights, etc.
when matching two sides in a potential war scenarip do not just calculate based and raw number of soldiers and weapon systems and types, training,etc on each side of the equation.
We must also see cultural, societal sysremic advantages and disadvantages each side has and look at it dispationately..
we must also keep track of the changes in the equation with time.
In conclusion, Usa will only be a useful tool for India against China for a decade Max.
it will actually be India that will China's major thorn of we play our cards right as USA has some inherent baked in hidden limitations and growing anchors which will incapacitate it soon. India better team up with Japan as it is all round going to give better push back and also concentrate on internal strengthening and indigenous capability.