A foul-mouthed outburst cost the new leader of Washington's key Pacific ally a chance to meet President Barack Obama in Laos on Tuesday. Duterte blasted Obama as a "son of a bitch" and warned he would not tolerate any violation of Philippines sovereignty he said such a question would entail, after which the White House canceled their planned parley.
While the nasty spat is not yet likely to damage the enduring relationship between the United States and the Philippines, and the countries' strengthening military cooperation in the shadow of China's rise, there is reason for Washington to be concerned.
The unpredictable new man in charge in Manila introduces an unwelcome element to an already tense region and is casting a late second-term cloud over painstaking effort by Obama to intensify relations between the allies.
More broadly, Duterte's anti-Americanism and haphazard diplomacy is worrying Washington's allies in the region. He has pledged not to bring up South China Sea territorial disputes in multilateral summits, moving closer to the position of Beijing that all parties should hold one-on-one talks with China that exclude the United States.
And that is likely to end up being a problem for the next US president. The new occupant of the Oval Office will face a regional policy challenge dominated by the assertive Chinese President Xi Jinping, who would leap at the chance to weaken US influence.
White House cancels meeting
Duterte and Obama had been due to meet on the sidelines of a regional summit in Laos. But the Filipino leader lashed out when asked by reporters how he would respond if Obama asked about human rights violations committed in his fearsome war on drugs gangs.
"I am a president of a sovereign state. And we have long ceased to be a colony of the United States," Duterte said, paraphrasing how he would address Obama. "Son of a bitch, I will swear at you."
The new Philippines president did not just obliterate the rules of behavior of the international leader's club with his remarks. He aimed a vulgarity at the President, which the White House could not stand for. Hence the meeting's cancellation.
"It was the right decision by President Obama. This was an offense against President Obama personally, but it was also an offense against the office of the Presidency of the United States," Nicholas Burns, the State Department's former third-highest official told CNN's "New Day" on Tuesday.
Donald Trump of the Philippines?
Duterte has been dubbed by some commentators as the Donald Trump of the Philippines, but even the US billionaire's often fiery rhetoric pales in comparison to the statements that regularly escape the lips of the former mayor of the city of Davao, who was elected in a landslide in May.
The White House clearly wanted to send a signal in its rebuke of Duterte that loose talk and bluster does not cut it on the international stage. Whether officials also had in mind someone closer to home who has made inflammatory statements on foreign policy -- the Republican presidential nominee -- was not clear.
"I think it was our judgment that given the focus and attention on President Duterte's comments leading into the meetings here we felt that didn't create a constructive environment for a bilateral meeting," Ben Rhodes, a deputy national security advisor told reporters in Laos.
Apparently prompted by the US move, Duterte quickly backtracked on Tuesday, saying he did not mean to insult Obama but was addressing a reporter.
But this was not the first time he's directed offensive language at American officials. In August, he called US ambassador to Manila Philip Goldberg a "gay son of a b****" and said Secretary of State John Kerry was "crazy."
Though Duterte's quick retreat after the White House reprimand showed that the US still can call shots in the relationship, it gave Republican vice presidential nominee Mike Pence an opportunity to attack Obama for squandering US "credibility" in the world.
But the administration has more to worry about than the political impact of Duterte's diatribe. That's because it can never be quite sure what he will do next.
"There has been a lot of concern primarily because I don't think there is a lot of understanding of the Philippine President or any way to predict what he is going to do," said Rodger Baker, vice president of strategic analysis at Stratfor, a geopolitical intelligence company. "It is that uncertainty that is causing the concern."
While the defense relationship, which is set to see US forces deploy to five bases in the Philippines to provide muscle to Obama's Asia pivot strategy, is not currently at risk, it could be seriously buffeted by a hostile president in Manila.
Some analysts believe that Philippine leaders' remarks represent a long-present streak of anti-Americanism that is inseparable from his worldview -- a scenario that suggests this week's controversy will not be the last of the Duterte era.
"This is a guy that came in already with a deep-seated suspicion of the United States," said Prashanth Parameswaran, associate editor of The Diplomat magazine and a Southeast Asia specialist.
"He is trying to craft what he calls an independent foreign policy for the Philippines. That is a very different line from where the (previous) Aquino administration was in when they came in. The relationship with the US was seen as very significant."
There are undertones in the US relationship with the Philippines that do not exist in other alliances Washington maintains in Asia. The United States claimed the archipelago from Spain following a war in 1898, so sovereignty issues are particularly acute. Even after independence, Washington kept a vast garrison in Subic Bay in the Philippines until being ordered to leave in 1992.
Duterte's recent offer to hold bilateral talks with Beijing on South China Sea claims has also scrambled the geopolitical game in the region, since it may complicate Washington's efforts to build a united front of allies opposed to Beijing's position.
These developments are especially dismaying to Washington since an international court in The Hague ruled against China's territorial claims in the South China Sea in July, saying Beijing had infringed the sovereignty of the Philippines.
The case, which pre-dates the current administration in Manila, was seen as a turning point in the South China Sea controversy -- but Duterte's unilateral approach could water down its impact.
War on drugs
Since he took office, more than 1,900 people have died, including at least 700 in police operations. The carnage has sparked alarm among human rights groups, which have complained about a wave of extrajudicial killings.
Sooner or later, the situation is likely to cause trouble in Washington when members of Congress are asked to continue supporting US military aid to the country.
The United States is also interested in ensuring that the current dispute does not harm anti-terror cooperation with the Philippines set up to hunt Al-Qaeda linked groups after the September 11 attacks in 2001 has been scaled back.
While the direction of US-Asia policy remains in doubt in the new administration, the next White House will face a delicate task in managing Duterte.
Manila is due to hold next year's ASEAN summit, and a festering showdown with the president -- and a continuing riot of death in the anti-drugs purge -- could make it difficult for a President Clinton or a President Trump to attend.
"The more optimistic read would be, it's still early days, this is a president who is just over two months into his presidency," said Parameswaran. "It will take a while for Duterte to find his footing on foreign policy, so the expectations for the relationship need to be dampened a little bit."