Philippine President Rodrigo Duterte represents a danger to the world. He has brutally executed those he believes are drug dealers, encouraging vigilantism. He completely disregarded due process. He also lashed out at President Obama. He is clearly a loose cannon that has the ability to say or do anything without regard to the consequences.
Any leader who is not willing to be questioned about their actions or policies is not trustworthy. All leaders need to be questioned. That is part of the checks and balances. If he says he doesn't want to be questioned, then he knows he's doing something that he cannot rationalize. He seems very egotistical, just like Donald Trump. He seems very "un-presidential," just like Donald Trump. What leader curses and says no one should question him, besides a dictator?
Duterte is not a danger to the world. He's just undiplomatic and very rude. With all due respect to the Philippines, the nation simply can not be a considerable danger to world security, economically or militarily. He might be a danger to those within his nation that he sends armed people after, but he's not a threat outside his borders.
Like a lot of people in power, President Duterte talks a big game but has very little to back it up. So what if he swears at our president, he's a grown man and has heard worse from haters right here in the United States. Duterte doesn't have a real military to back him up.