In the past few days, Duterte’s compared himself to Hitler, threatened “breaking up” with the United States and said he plans to kill millions of addicts in an intense war on drugs.
Claude Rakisits, a professor at Georgetown University's School of Foreign Service specializing in Pacific Studies and a South Asia Center Fellow at the Atlantic Council, believes Duterte calls Obama names to protect his image in the Philippines. "He wanted to appear tough," Rakisits said.
But the professor thinks the move is simply bad politics. “[The names he called President Obama] are names that you wouldn’t want to repeat to your children."
What could this mean for U.S.-Philippines relations?
In a speech at a Makati city synagogue in Manila, Duterte warned that he may "break up with America" and turn instead to China or Russia.
"International relations is not between individuals," Rakisits said. "It's between countries."
Sheena Greitens, a senior fellow with the Center for East Asia Policy Studies at the Brookings Institute and an assistant professor of political science at the University of Missouri, believes that "the best U.S.-Philippines alliance would be one where the benefits are clearly recognized by the public and the citizens of both countries."
She finds that today's controversy stems from a "change in the consequences of rhetoric" that happen when a leader moves from being a localized figure, as Duterte was as a mayor and then presidential candidate, to being a president and an international figure. "That shift has been rocky in terms of the effects on U.S.-Philippines relations," Greitens said.
What is the Philippines' war on drugs and why is it controversial?
Ever since he took office in June of this year, Duterte has made every effort to effect an intense war on drugs, based primarily in the killings of drug addicts throughout the country.
How is the relationship between the U.S. and the Philippines today?
In the Philippine-American War, Spain ceded the Philippines, which was previously its own colony, to the United States. Filipino nationalists led by Emilio Aguinaldo sought independence instead of a new colonizer, leading to a three-year war from 1899 to 1902.
"We're confident that that will continue, and we continue to work closely with the Philippine military on a range of fronts."
How do Filipinos feel?
Duterte ran on a strong anti-crime platform, promising to be tough on drugs, which was how he built a strong national reputation.
Some Filipinos, however, are drawing parallels to the anti-crime platform that elected dictator Ferdinand Marcos. He came into power by popular election this way, and then turned to martial law.
Natalia Peña is a student at Georgetown University and grew up in a highly politically-minded household in Makati. Her father, Fernando Peña, was a renowned anti-Marcos activist and freedom fighter who won a medal of valor. Peña finds Duterte's recent statements, his war on drugs and his plans for relations with Russia and China unbelievable.
"As for the war on drugs, I am sad and disappointed. Saddened by the possibility that it might possibly become 'normal' for someone to 'disappear' and that our country democratically chose this reality."
She doesn't believe extrajudicial killings are an answer and sees a need for due process instead.
"We do not need a repeat of Martial Law. We already fought for our freedom, and if we need to fight for it again we will."
Some experts, like Rakisits, are "not sure how long he's going to last -- he's a strange guy."