MANILA (Reuters) - Philippine President Rodrigo Duterte on Thursday accused the United States of having a provocative stance on the South China Sea and said its inaction when China started building manmade islands was the cause of tensions now besetting the region.

Philippine President Rodrigo Duterte gestures while answering questions during a news conference upon arrival from a trip to Myanmar and Thailand at an international airport in Manila, Philippines March 23, 2017. REUTERS/Romeo Ranoco

Duterte said Washington’s freedom of navigation patrols risked a “miscalculation” that could spark conflict, and accused the previous U.S. administration of pressuring the Philippines to take a stand against China, without a guarantee of military support.

“You go there in the pretence of challenging them?” he said of the U.S. patrols that began under the Obama administration. “One single solitary shot, it could lead to an explosion and it could lead to a war and it will be a slaughter.”

The firebrand leader is open about his grudge against his country’s oldest ally, which he said was bound by a treaty to protect the Philippines, but had done nothing when China started building in parts of Manila’s its exclusive economic zone (EEZ).

“Why in hell, America, the only one who can act there, why did it want my navy to go there? It will be a massacre for my soldiers,” he told an audience of lawyers.

“Why did you not, the first instance, go to Chinese working there, building structures there?”

He added: “Why did you not reprimand them? Why did you not send five aircraft carriers? And you had to wait for the problem to ripen to an international issue involving, this time, so many countries.

“You could have cut the problem in the bud had you taken a decisive action.”

Duterte’s comments came amid concern in the Philippines that China would build several environmental monitoring stations in disputed waters, including on the Scarborough Shoal 124 miles off the Philippine coast. China has dismissed that as “not true”.

The United States insists it wants to preserve freedom of navigation and oversight in the strategic waterway and that its actions are not a provocation.

SURPRISE OVERTURES

In contrast to his tirade against Washington, Duterte did not criticize China, which he is trying to cultivate as a buyer of farm produce, and builder of its infrastructure.

His overtures toward a country long regarded by Manila as a maritime aggressor marked an astonishing foreign policy shakeup. Recalling his remarks at an October meeting with Chinese counterpart Xi Jinping, he said the two had a lot in common.

“I decided to change a little bit our foreign policy,” he said.

“Why is it that we are too far from trade and commerce with China? They said we are Americans. Said who? - China.

“I went to China, (and said) ‘I don’t like Americans, we’re the same. I came to shake your hand and if I can have participation in trade and commerce’.”

He invited China to send a battleship to visit the Philippines and suggested sharing offshore energy resources in the Philippine EEZ that China lays claim to.

“Even if I like to claim it all, I have no capital, even the rigs and everything, we cannot afford it,” he said.

Duterte said it was pointless trying to challenge China’s fortification of its manmade islands and ridiculed the media for referring to a comment he made during his election campaign, when he said he would ride a jet-ski to one Beijing’s reclaimed reefs, and put a Philippine flag there.

“We cannot stop them because they are building it with their mind fixed that they own the place. China will go to war,” he said. “People want me to jet ski. These fools believed me.”