Washington   -   Donald Trump has blamed Iran for recent attacks on two oil tankers near the strategic Strait of Hormuz, describing the country is a “nation of terror”.

Speaking with Fox News on Friday, the president rejected Tehran’s denials that it was involved in the attacks and cited a video released by US Central Command late Thursday purporting to show an Iranian vessel removing an unexploded mine from one of the tankers.

“Iran did do it and you know they did it because you saw the boat,” Trump said. “They’re in deep, deep trouble.”

“We don’t take it lightly,” he added, pointing out the US had already reimposed tough sanctions on Iran. “They’ve been told in very strong terms … we want to get them back to the table if they want to get back. I’m in no rush.”

Trump’s comments came during a wide-ranging interview with Fox & Friends on his 73rd birthday.

Hours before Trump’s interview aired, Iran’s foreign minister, Mohammad Javad Zarif, said the US was making allegations without “a shred of factual or circumstantial evidence” and accused the Trump administration of “sabotage diplomacy”.

The U.S. military also released a video Friday it said showed Iran’s Revolutionary Guard removing an unexploded limpet mine from one of the oil tankers targeted near the strategic Strait of Hormuz, suggesting Tehran wanted to hide evidence of its alleged involvement.

Iran denied any role in Thursday’s apparent attacks, which have again roiled the Persian Gulf amid heightened tensions between Tehran and Washington over the unraveling nuclear deal with world powers.

Four other oil tankers off the nearby Emirati port city of Fujairah suffered similar attacks in recent weeks, and Iranian-allied rebels from Yemen have struck U.S. ally Saudi Arabia with drones and missiles.

The black-and-white U.S. video of the Iranians alongside the Japanese-owned tanker Kokuka Courageous came after its crew abandoned ship after seeing the undetonated explosive on its hull, said Capt. Bill Urban, a spokesman for the U.S. military’s Central Command. It separately shared photos of the vessel, which showed what appeared to be a conical limpet mine against its side.

In the video, the boat from Iran’s paramilitary Revolutionary Guard pulls alongside Kokuka Courageous at 4:10 p.m. Thursday. The Iranians reach up and grab along where the limpet mine could be seen in the photo. They then sail away.

Limpet mines, which are magnetic and attach to a ship’s hull, are designed to disable a vessel without sinking it.

Analysts say Iran, if involved, wouldn’t want investigators to find an unexploded mine because they could check its serial numbers and other attributes to trace it.

“The U.S. and the international community stand ready to defend our interests, including the freedom of navigation,” Urban said in a statement. “The United States has no interest in engaging in a new conflict in the Middle East. However, we will defend our interests.”

In a statement from its U.N. mission, Iran accused the U.S. of escalating tensions. “The U.S. economic war and terrorism against the Iranian people as well as its massive military presence in the region have been and continue to be the main sources of insecurity and instability in the wider Persian Gulf region and the most significant threat to its peace and security,” the statement said.

Trump’s appearance on Fox & Friends came as he capped off yet another week mired in controversy. Trump ignited a firestorm on Wednesday by stating he would listen if a foreign government approached his campaign with damaging information about a political opponent.

Meanwhile, German Foreign Minister Heiko Maas said video provided by the United States is not sufficient to prove that Iran is behind the attacks on oil tankers in the Gulf of Oman,

“The video is not enough. We can understand what is being shown, sure, but to make a final assessment, this is not enough for me,” Maas told reporters during a visit to Oslo.