US Treasury Secretary Scott Bessent called Iran's so-called Strait Authority a “joke”, after Washington placed sanctions on the body Tehran recently established to manage the Strait of Hormuz.Iran's top security body in a post on X last week announced the formation of the Strait Authority to control the waterway, which Tehran has effectively closed since March and wants to charge a toll for ships to navigate through it.In the post, Tehran claimed regulatory jurisdiction over “the line connecting Kuh-e Mubarak in Iran to the south of Fujairah in the UAE at the eastern entrance of the Strait, to the line connecting to the tip of Qeshm Island in Iran to Umm Al Quwain in the UAE at the western entrance”.The Treasury Department said anyone co-operating with the body could be providing and receiving services from Iran's Islamic Revolutionary Guard Corps, exposing them to risk of US sanctions violations.“Iran's Strait Authority is a joke, and today we have sanctioned it,” Mr Bessent said in a post on X. “We have warned any corporate or state entities against paying tolls or hiding them as aid payments.”In the same post, Mr Bessent said the US would be shutting down both Iranian airlines' access to landing spots, refuelling and ticket sales.The sanctions were announced on Wednesday as part of the Treasury Department's “Economic Fury” campaign, which is part of President Donald Trump's “maximum pressure” approach.“The Iranian economy and currency are in freefall,” Mr Bessent said.The effective closure of the Strait of Hormuz, through which about 20 per cent of the world's energy supply passes, has rattled oil markets and the global economy. Recent projections from the International Monetary Fund point to slower economic growth and higher inflation because of the closure, while the fund has also warned prolonged disruptions would lead to sharper economic consequences.Oil prices have receded in recent days on hopes that a deal between Washington and Tehran is within reach, although Brent crude is still trading more than 30 per cent its prewar level.“We are in the midst of the largest energy security crisis the world has ever faced – and I believe this will reshape investment strategies globally, with parallels to the major changes the energy world witnessed after the oil shocks of the 1970s,” International Energy Agency executive director Fatih Birol said in the body's latest World Energy Investment.The IEA, World Bank and IMF last month announced a co-ordinated response to support energy-vulnerable economies most impacted by the conflict. The IMF has previously said it expects demand for new programmes to range between $20 billion and $50 billion, with more than a dozen countries expressing interest.In a separate post on Thursday, Mr Bessent warned Oman that Treasury would “aggressively” attack any actors involved in enabling tolls in the strait. The statement comes a day after Mr Trump threatened to attack Oman following reports from Iranian state media saying Tehran and Muscat would jointly manage traffic in the waterway.“It's international waters and Oman will behave just like everybody else or we'll have to blow them up,” Mr Trump said during a Cabinet meeting.The US has also implemented a naval blockade of Iranian ships in the strait. Mr Trump on Sunday said the blockade would remain in place as he signalled he is not in a rush to come to an agreement with Tehran.