When an Iranian official this week laid out a list of demands to end the war started by the United States and Israel, he added an item that hadn’t been on Tehran’s list before: recognition of Iran’s sovereignty over the Strait of Hormuz.

The narrow waterway through which a fifth of the world’s oil and liquefied natural gas (LNG) ordinarily passes has emerged as the Islamic Republic’s most potent weapon. And it is now seeking to turn into both a source of potentially billions of dollars in annual revenue and a pressure point on the global economy.

Iran has long threatened to close the strait in case of an attack, but few expected it to follow through – or for it to prove so effective in disrupting global trade flows. The scale of the impact appears to have expanded Tehran’s ambitions, with the new demands suggesting it is seeking to turn that leverage into something more durable.