It has been unclear how the multi-deck pleasure vessel, worth over $500 million, gained permission to sail on Saturday through the ​commercially important waterway at the heart of the US-Iran conflict, ​where traffic has been severely restricted since February.

Sailing under a ⁠Russian flag, the yacht, called Nord, crossed the strait on an ​approved route in compliance with international maritime law, the source said.

“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 said.

Just ‌a ⁠few, mainly merchant vessels, have been passing daily through the crucial waterway at the entrance to the Gulf as Washington and Tehran maintain an uneasy ceasefire. This represents a fraction of the average 125 to 140 ​daily passages before the ​Iran war ⁠began on February 28. In response, the U.S. has imposed a blockade of Iranian ports.

Russia is a ​longstanding ally of Iran. Iranian Foreign Minister Abbas Araqchi ​travelled to ⁠St Petersburg on Monday for a meeting with Russian President Vladimir Putin, after discussions with peace mediators in Pakistan and Oman over the ⁠weekend.

After crossing ​the Strait, Nord has been located near ​the coast of Oman since Sunday, according to LSEG data.