Most likely avenues for a war with China imo;

1. Most likely, they flood Taiwan with military spending ala ukraine and try to encourage sepratist sentiment
2. They try to encourage a sino-vietnam split
3. (this is already happening) they manipulate the indonesian/PNG war to prolong it and encourage China to over-extend, sort of like there strategy with the USSR and Afghanistan.

All three of the above are happening already, just if they go 'all in' on one of these is yet to be seen, so far its just half assed laying the groundwork type shit.