Sailors transferring fuel oil from an Iraqi tanker in the Arabian Gulf to another vessel discovered a “suspicious object” they fear could be a mine. The discovery, reported by authorities on Thursday, comes amid heightened tension between Iran and the US in the waning days of President Donald Trump’s administration. Already, America has conducted B-52 bomber flyovers and sent a nuclear submarine into the Arabian Gulf over what Trump officials describe as the possibility of an Iranian attack on the first anniversary of the US drones strike in Baghdad that killed Iranian general Qassem Suleimani. Two private security companies said sailors feared they found a limpet mine on the <em>MT Pola</em>, a Liberian-flagged tanker owned by a shipping company traded in the US. The <em>Pola </em>was receiving assistance on Thursday in the waters off Basra. A limpet mine is a type of naval mine that is attached to the side of a ship, usually by a military diver. It later explodes, and can significantly damage a vessel. The two companies, Ambrey Intelligence and Dryad Global, say investigations are ongoing. United Kingdom Marine Trade Operations, an organisation under Britain’s Royal Navy, said on its website that an unknown object had been attached to a ship’s hull in the vicinity of Iraq’s Khor Al Zubair Port. The US Navy’s 5th Fleet, which patrols the Middle East, was monitoring the incident, said spokeswoman Cmdr Rebecca Rebarich. An Iraqi official declined to immediately comment. The <em>Pola</em>, along with another tanker, serves as floating fuel oil storage of Iraq's State Organisation of Marketing of Oil, said Sudharsan Sarathy, a senior oil analyst at the data analysis company Refinitiv. Smaller vessels carry the fuel oil to the ship, which then conducts ship-to-ship transfers in the Arabian Gulf to clients. Mr Sarathy said the <em>Pola </em>was conducting a ship-to-ship transfer with the <em>MT Nordic Freedom</em>, a Bermuda-flagged tanker. Dryad Global posted a satellite photo it said showed the <em>Pola </em>and the <em>Nordic Freedom</em>. Stocks in the <em>Nordic Freedom</em>'s owner, Nordic American Tankers, traded slightly down early on Thursday on the New York Stock Exchange at slightly under $3 a share. In 2019, the US blamed Iran for a series of limpet mine attacks on oil tankers near the Strait of Hormuz, the narrow mouth of the Arabian Gulf through which 20 per cent of the world’s oil passes. Tehran denies being involved. Iranian Foreign Minister Javad Zarif on Twitter earlier on Thursday criticised Mr Trump for wasting “billions to fly B52s & send armadas to our region”. “Intelligence from Iraq indicate plot to fabricate pretext for war,” Mr Zarif wrote. “Iran doesn’t seek war but will openly & directly defend its people, security & vital interests.”