Iran's Revolutionary Guards said on Wednesday they thwarted an attempt by the United States to detain a tanker carrying the Islamic Republic's oil in the Sea of Oman. US officials, speaking on condition of anonymity, said that the Iranian report was not true and there had been no American attempt to seize a tanker. The American officials said that in reality Iranian forces had seized a Vietnamese-flagged oil tanker last month and US naval forces were just monitoring the situation. "With the timely and authoritative action of the Guards naval forces, the US terrorist Navy's operation to steal Iranian oil in the Sea of Oman failed," the elite Guards said in a statement published by Iranian state media. Read more: Top military official blames US, Israel for Iran cyberattack "The tanker carrying Iran's oil docked at the port of Bandar Abbas on October 25." While Iranian media identified the seized tanker as "SOTHYS" — the name tanker tracking websites give for a Vietnam-flagged vessel — state TV aired footage showing a red tanker surrounded by about 10 speed boats. It also included a recording of what TV said was the encounter between Iranian and US forces. Iran has repeatedly warned the United States about its military activities in the Gulf, saying that the Guards' naval forces have increased patrols to also secure the passage of Iranian ships and combat fuel smuggling. Drones Giving details of the reported incident, Press TV said the Guards had reacted "promptly" when the Iranian oil tanker was detained in the Sea of Oman. "Members of the Guards naval forces carried out a heliborne operation on the detained tanker's deck, gained control of the vessel, and directed it back toward Iran's territorial waters," Press TV reported. Also read: US targets Iran's drone programme with sanctions Separately, American officials told Reuters that several drones, believed to be Iranian, had come close to the US Navy amphibious assault ship Essex in the Strait of Hormuz in the past 24 hours. Tensions have risen between Tehran and Washington amid stalled talks on reviving Iran's 2015 nuclear deal with world powers, under which Tehran curtailed its uranium enrichment programme in exchange for a lifting of global sanctions. Iran's top security official Ali Shamkhani said on Wednesday the talks would fail unless US President Joe Biden could guarantee Washington would not renege on the nuclear agreement in the future. The deal has eroded since 2018 when then-President Donald Trump withdrew the United States from it and reimposed US sanctions on Iran, prompting Tehran to breach various limits on uranium enrichment set by the pact. Shamkhani tweeted: "The US president, lacking authority, is not ready to give guarantees. If the current status quo continues, the result of negotiations is clear."