WASHINGTON (Reuters) - The U.S. military released a video late on Thursday that it said showed Iran’s Revolutionary Guard (IRGC) removing an unexploded mine from the side of a Japanese-owned oil tanker, as Washington blamed Iran for attacks rattling global oil markets.

The U.S. military’s Central Command also released photographs showing the apparent mine, which attaches to the side of a ship magnetically, before it was removed later in the day.

Such imagery is often difficult to declassify and its release appeared to show U.S. efforts to convince the international community of Iran’s culpability in Thursday’s attacks on the Kokuka Courageous and the Norwegian-owned Front Altair. Tehran has bluntly denied the allegation.

Both vessels suffered explosions, forcing crews to abandon ship and leave them adrift in waters between Gulf Arab states and Iran.

Navy Captain Bill Urban, a Central Command spokesman, said the IRGC vessel was observed at 4:10 p.m. local time approaching the Japanese-owned tanker.

“(It) was observed and recorded removing the unexploded limpet mine from the Kokuka Courageous (video attached),” Urban said in a statement.

Reuters had previously reported the existence of the video.

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Crude oil prices spiked more than 4% after the attacks near the entrance to the Strait of Hormuz, a crucial shipping artery for Saudi Arabia and other Gulf energy producers. Prices later settled about 2% higher. [O/R]

Brent crude [LCOc1] was down by 0.4% at $61.06 a barrel in early Asia trading.

Central Command also offered a detailed chronology of events, starting with U.S. Navy forces receiving distress calls from the Altair at 6:12 a.m. and from the Kokuka Courageous at 7 a.m.

But much of the chronology centered on the movement of nearby Iranian ships, and what Central Command said was an Iranian order to take control of Altair sailors who had been rescued.

About an hour after the Kokuka Courageous’ distress call, a U.S. aircraft observed an IRGC Hendijan-class patrol boat and multiple IRGC fast attack craft and fast inshore attack craft near the Altair, Urban said.

He said that at 9:26 a.m. Iranian forces told a ship that had rescued sailors from the Altair “to turn the crew over to the Iranian (fast inshore attack craft).”

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“The motor vessel Hyundai Dubai complied with the request and transferred the crew of the Altair to the Iranian (vessels),” Urban said.

In a statement on Thursday evening, the Iranian mission to the United Nations said Tehran “categorically rejects the U.S. unfounded claim with regard to 13 June oil tanker incidents and condemns it in the strongest possible terms.”

It accused the United States and its regional allies, which include Iranian rival Saudi Arabia and the United Arab Emirates, of “warmongering.”

Urban said the United States would defend its interests and warned that Thursday’s attacks were a threat to international freedom of navigation and freedom of commerce.

“The United States has no interest in engaging in a new conflict in the Middle East,” Urban added. “However, we will defend our interests.”