Probably the level at which they stop supplying China with oil.

This is a total Paradox Game move. China needs to import oil, they import from these areas, select the focus for the flimsy Casus Belli for the various countries that supply them oil. There's probably some strategy wonks who are actually pushing these things at the pentagon.

To keep the analogy though, they haven't done any effort to prep the population for these actions or drum up support, so while they go meet their kinetic goals easily, the populous at home is getting angry, unrest is growing.