I would simply stop all government-to-government contacts. US troops should be withdrawn from Mindanao (and everywhere else in the country) within a week or less - whether Philippine government is ready to take over or not. Embassador should be recalled for indefinite consultations, with a junior diplomat left in charge of skeleton staff. Phone calls should be returned by junior officials. US businessmen should be proactively informed that US government will not be able to protect their interests in any way if anything goes wrong. Philippines are of insufficient importance to the US to bother much in this case. If China wants to take over as their main protector, it should be welcome.
And, of course, the fact that Israel still has an embassador in Manila is a sign of how hypocritical that country´s government is. Had a head of any Muslim or European state said something 1/10th as offensive, they would have been jumping up and down in fake rage. They seem to be pretty damn silent.
The problem is Duterte seems more than willing to let this happen. Willing to bury the South China Sea issue, even. Chinese Ambassador gave a speech, could hardly contain his delight.
