It sounds pretty simple: if negotiations with Iran over its nuclear program stall/don’t restart/break down, put together a sanctions package on Iran’s oil
“„But enforcing what would amount to a gasoline embargo has long been considered risky and extremely difficult; it would require the participation of Russia and China, among others that profit from trade with Iran. Iran has threatened to respond by cutting off oil exports and closing shipping traffic through the Strait of Hormuz, at a moment that the world economy is highly vulnerable.
