Duterte's tongue the least of Obama's Philippine problem

It's not just a runaway tongue that worries the United States about the volatile new president of the Philippines, Rodrigo Duterte. It's what else he's thinking.

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.

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.

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.