A superyacht owned by one of Vladimir Putin’s key allies passed through the Strait of Hormuz as the critical waterway remains effectively closed to commercial ships.

“Nord,” a 465-foot multi-deck luxury vessel valued at more than $500 million linked to Russia’s richest man, Alexei Mordashov, was able to navigate the Strait after undergoing maintenance in Dubai, after neither Iran nor the US objected, a source close to the billionaire said Tuesday.

Sailing under a Russian flag, the yacht left Dubai on Friday and passed through the Strait on Saturday, one of the few private vessels to successfully do so since the start of the war in Iran.

It arrived at Oman’s capital Muscat on Sunday morning according to data on the Marine Traffic platform.

“Iran did not interfere with the movement of the yacht, as it is a civilian vessel of a friendly country conducting a peaceful transit. The American side also raised no questions regarding the yacht’s movement, as it did not call at Iranian ports and has no connection to Iran,” the source told Reuters.

Iran has choked off traffic to the Strait and the US has an ongoing naval blockade of the passage.

Just a handful of ships, mostly merchant vessels, have been able to pass through the Strait, the crucial waterway in the Persian Gulf through which normally passes a fifth of the world’s oil and natural gas shipping.

This is a fraction of the 125 to 140 average journeys made through the Strait before the start of the war on Feb. 28.

Mordashov, 60, the CEO of Russia’s largest steel and mining company, Severstal, has an estimated net worth of around $37 billion, according to Forbes.

“Nord,” one of the world’s most expensive superyachts, features two helicopter pads, luxury lounge decks, and an 80-foot swimming pool at the stern.

It also includes an onboard gym, cinema, and jacuzzi, and carries a submarine and other smaller craft.

The ship has space for 36 guests and 42 crew.

Mordashov is not listed as the “Nord’s” formal owner, but records indicate it was registered to a firm owned by his wife in 2022.

Vladimir Putin has been a long-time ally of Iran, and held high-level talks on Monday in St Petersburg with the Iranian Foreign Minister, Abbas Araghchi, following talks in Pakistan and Oman over the weekend.

Mordashov, a strong supporter of the Russian President, has faced Western sanctions over his funding of the war in Ukraine.

In March 2022, in the early days of the war, one of Mordashov’s smaller boats, the 215-foot “Lady M,” was impounded by Italian police in the port of Imperia.