WASHINGTON/ DUBAI — US Secretary of State Mike Pompeo blamed Iran on Sunday for last week's attacks on oil tankers and vowed that the United States will guarantee free passage through the vital Strait of Hormuz.

Pompeo would not be drawn on what options the US is considering to protect shipping — or to punish Iran — in the wake of Thursday's attacks on two tankers in the Gulf of Oman.

"What you should assume is we are going to guarantee freedom of navigation throughout the strait," he said in an interview on "Fox News Sunday."

A third of the world's seaborne oil supply passes through the Strait of Hormuz, a narrow channel bordered to the north by Iran that links the Gulf with the Gulf of Oman.

"This is an international challenge, important to the entire globe. The United States is going to make sure that we take all the actions necessary, diplomatic and otherwise, that achieve that outcome," Pompeo said.

He would not lay out US evidence for Iran's involvement in the Gulf of Oman explosions, but insisted: "It's unmistakable what happened here.

"These were attacks by the Islamic Republic of Iran on commercial shipping, on the freedom of navigation, with the clear intent to deny transit through the strait."

Meanwhile, the two damaged tankers arrived safely Sunday at locations off the Emirati coast after they were rocked by explosions in Gulf waters, in an incident Saudi Arabia blamed on its regional arch-rival Iran.

The Japanese-owned Kokuka Courageous was carrying highly flammable methanol through the Gulf of Oman on Thursday when it came under attack along with the Norwegian-operated Front Altair — the second assault in a month in the strategic shipping lane.

US President Donald Trump has said the operation had Iran "written all over it" — rejecting Tehran's vehement denial — and its key Gulf ally Saudi Arabia has also lashed out against Tehran.

In his first public comments since the attacks, Saudi Crown Prince Muhammed Bin Salman said in remarks published Sunday that he would not hesitate to tackle any threats to the Kingdom.

"We do not want a war in the region... But we won't hesitate to deal with any threat to our people, our sovereignty, our territorial integrity and our vital interests," he told pan-Arab daily Asharq al-Awsat.

He said Iran had responded to a visit to Tehran by Japan's Prime Minister Shinzo Abe "by attacking two tankers, one of which was Japanese".

The US military on Friday released grainy footage it said showed an Iranian patrol boat removing an "unexploded limpet mine" from the Japanese vessel.

The crew of the Kokuka Courageous saw a "flying object" before a second blast on board, the operator's head said Friday.

The vessel's Singapore-based BSM Ship Management said in a statement Sunday that it had "arrived safely at the designated anchorage" and that its crew were "safe and well".

The other ship, the Front Altair, was under safe tow by tug boats towards an area off the coast of the eastern Emirati port of Fujairah.

"First inspections are under way and no hot spots have been identified following the fire," the vessel's owners said in a statement Sunday.

It said all crew members were in Dubai, where they will "assist with the debrief to the owner's legal team and the appropriate authorities, before returning home".

The UAE's Foreign Minister Sheikh Abdullah bin Zayed Al Nahyan on Saturday called on world powers "to secure international navigation and access to energy". — AFP