CNN ONLINE

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.

“Iran has been a little taken aback by how successful its (Hormuz) strategy has been – by how cheap and how comparatively easy it is to hold the global economy hostage,” said Dina Esfandiary, Middle East lead at Bloomberg Economics.

Washington is acutely aware of that risk. US Secretary of State Marco Rubio warned Friday that one of the immediate challenges following the war would be Tehran’s attempts to establish a tolling system at Hormuz.

In a nod to the growing strategic weight of the Strait of Hormuz, Mojtaba Khamenei used his first purported address as Iran’s new supreme leader to say that the leverage of blocking the waterway “must continue to be used.”

In previous rounds of talks with the US, Iran pushed for sanctions relief and recognition of its right to peaceful nuclear technology but not control over the Strait of Hormuz.

Iran is now signaling that this leverage could be formalized. Iranian lawmakers are considering a bill that would require countries using the strait for shipping fuel and goods to pay tolls, while an adviser to the supreme leader has spoken of a “new regime for the Strait of Hormuz” after the war.

This new system would allow Tehran to impose maritime restrictions on adversaries and effectively tie access to one of the world’s most critical shipping lanes to its geopolitical disputes.

“Imposing transit fees is a violation of the rules of transit passage,” said James Kraska, a professor of international maritime law at the US Naval War College. There is no legal basis under international law for a coastal state to charge fees in an international strait like Hormuz, he added.