A tanker seized by the US for carrying sanctioned Iranian crude oil has begun offloading its cargo despite Tehran’s threats against shipping shipping companies.

The Associated Press cited tanker-tracking data on Sunday that showed the oil cargo is being transferred from Marshall Islands-flagged Suez Rajan, a tanker anchored off the coast of Texas, near Galveston about 50 miles (80 km) from Houston.

The owners of the Suez Rajan, the Los Angeles-based private equity firm Oaktree Capital Management, did not immediately respond to requests for comment about the ship-to-ship transfer.

On Wednesday, a bipartisan group of US lawmakers from the House and Senate asked the Biden administration to respond to “unprecedented intimidation” tactics from Iran that have prevented American firms from offloading the confiscated oil cargo.

The US seized the Iranian oil onboard the ship late in May in accordance with US sanctions, but the oil had reportedly not been offloaded as US federal prosecutors have faced challenges in auctioning off the 800,000 barrels of oil. The lawmakers estimated the value of the oil to be $56 million.

According to the Wall Street Journal, the US companies are reluctant to unload the oil due to concerns about potential Iranian reprisals, particularly threats of violence by Iran’s Revolutionary Guards. Iran's IRGC navy commander Alireza Tangsiri warned in July that Tehran would retaliate against any oil company involved in unloading the Iranian oil.

The US Navy has increased its presence steadily in recent weeks in the Mideast, sending the troop-and-helicopter-carrying USS Bataan through the Strait of Hormuz in recent days and considering putting armed personnel on commercial ships traveling through the strait to stop Iran from seizing additional ships.