Philippines, possibly - depending on who you talk to. https://www.brookings.edu/...

bpodgursky · on Feb 8, 2017

The US has tons of bases on the Philippines and there's a lot of training/cooperation. I can't imagine that the US didn't have permission and cooperation there, if it happened.

FWIW the Philippine military denies that it happened -- http://news.abs-cbn.com/nation/07/09/12/philippine-military-.... Which is at odds with objecting to it.