In a bar along the Philippines' Subic Bay owned by an American military veteran, the main topic of conversation is not the upcoming U.S. election despite the Donald Trump coffee mugs, photographs and caps on display.

The talk is of Philippines President Rodrigo Duterte's tensions with Washington and his courting of China, which is worrying the bar's mostly American clients who have settled in the vicinity of the huge Subic Bay base, a former U.S. Navy installation.

"The biggest fear is that one day he's going to wake up and say 'everybody from the U.S., get out of town' and we'd have to leave our loved ones behind," said Jack Walker, a retired marine sergeant who has lived in Olongapo, the town around the base, for five years.