US federal prosecutors have faced challenges in auctioning off 800,000 barrels of seized Iranian oil aboard a Greek tanker off the coast of Texas.

According to the Wall Street Journal, the US companies are reluctant to unload the oil due to concerns about potential Iranian reprisals.

“Companies with any exposure whatsoever in the Persian Gulf are literally afraid to do it,” said a Houston-based energy executive involved in the matter, citing worries “that the Iranians would take retribution against them.”

This impasse sheds light on the difficulties the US government encounters in enforcing sanctions against Iran, especially as Iran has escalated its attacks against Western shipping interests as a deterrent to interdicting Iranian exports.

These tactics are seen as Tehran's strategy to prevent the West from interfering in its economic activities, added the report.

The issue comes at a time when US diplomats are quietly attempting to restart negotiations with Iran over a nuclear accord.

“That vessel’s emblematic of a much bigger drama that’s playing out about how we deal with Iranian threats,” a former US official told WSJ.

Tehran's military forces have hijacked several Western tankers in recent months, seen as retaliation for Western seizures of Iranian oil.

Meanwhile, the US Defense Department said Monday that it is deploying F-35 jet fighters and a Navy destroyer to the Middle East as a measure to deter Iran from attempting further seizures and to address Russian aggression in the region.