Iran’s Revolutionary Guards said Thursday they had detained a “foreign tanker” for allegedly smuggling fuel. "With a capacity of two million barrels and 12 foreign crew on board, the vessel was en route to deliver contraband fuel received from Iranian boats to foreign ships in farther regions when it was intercepted," the forces Sepahnews website said. It was seized south of the Iranian island of Larak, the Guards said, without detailing the name or provenance of the vessel. The United States condemned the development. “The United States strongly condemns the Revolutionary Guard Corps Navy’s continued harassment of vessels and interference with safe passage in and around the Strait of Hormuz,” the spokesperson added in an email to Reuters after Iran said it had seized a foreign tanker smuggling fuel in the Gulf. “Iran must cease this illicit activity and release the reportedly seized crew and vessel immediately.” The Guards statement came after officials said Iran had come to the rescue of an ailing tanker on Sunday. "Iranian forces approached it and using a tugboat brought it into Iranian waters for necessary repairs," foreign ministry spokesman Abbas Mousavi said. Oil shipping monitor TankerTrackers reported that the Panamanian-flagged tanker Riah, used in the Strait of Hormuz "for fueling other vessels", had crossed into Iranian waters on Sunday. The Guards did not confirm whether the vessel they had detained Sunday in the highly sensitive Strait of Hormuz was the same ship as that mentioned Tuesday by the foreign ministry. The incident is the latest of a series of events that have raised fears of a regional conflict involving the US and its Gulf allies. US President Donald Trump ordered air strikes against Iran in June after Tehran downed an American drone, but called them off at the last minute. Washington has blamed Tehran for a series of tanker attacks in recent months in the Gulf, charges Iran denies. US Central Command chief Kenneth McKenzie pledged Thursday to work "aggressively" to ensure freedom of navigation in the highly sensitive Gulf waters, a conduit for much of the worlds crude oil. "We are going to work very aggressively with our partners... to come to a solution that will enable the free passage of critical oil and other commodities... through the region," McKenzie said. The tensions come after Trump last year withdrew from a multinational deal under which Iran drastically scaled back its nuclear program in exchange for relief from sanctions.