They can't, the ships are 1 mile outside of their EEZ.Pretty much. Follow proper procedure, fire a warning shot, if they don't stand down, sink them. Then you force them back to your port, where you seize their vessels, and either throw them in the slammer or deport them.
What's the Chinese Navy going to do, send a fleet to Galapagos?
Sure, they could send a couple of small/mid-sized ships, but not enough to keep the South Americans from fighting back effectively, much less if the US tells them 'get away from our side of the Pacific.'