Blackstone
Brigadier
US position since Brenton Woods is it's neutral on territorial sovereignty disputes of foreign countries. No ifs, ands, or buts about it. Tillerson, on the other hand, is doing a 180 on that, and it's unclear if that applies it to only China or to others too.Of course it would mean war.
China claims those islands as its own, and has stationed them with both civilian and military personnel. China has even created a municipal district to administer the region.
In order to do what Tillerson is proposing, the US would have to either invade those islands or blockade them with their navy. Both actions would be acts of war.
It's possible Tillerson misspoke or went beyond his initial instructions from Trump, but assuming he's carrying out Trump's vision in the SCS, then China and the US will have a tense relationship, until a new equilibrium is reached. Graham Allison said about 3 in 4 equilibrium adjustments between established and rising great powers took the form of wars, I hope we're in the 25%.