Two years after Philippine President Rodrigo Duterte announced a divorce with old ally the United States in return for bumper business ties with China, he doesn't have much to show for it.

Duterte left Beijing in 2016 with $24 billion of Chinese loans and investment pledges for his ambitious infrastructure overhaul, a few weeks after saying the Philippines was being treated like a dog by Washington and would be better off with China.

But only a fraction of China's pledged support has materialized, exposing Duterte to criticisms he has been complicit in allowing China to pose threats to Philippines' sovereignty, and been left high and dry by Beijing.