Of course it is prudent to be cautious when dealing with a country like Iran, which has reneged on its nuclear promises in the past. No significant sanctions relief should be afforded to Tehran until the IAEA can categorically say that the country has complied with the deal. There are also US regulatory approvals that have to be cleared. Secondary sanctions imposed by Washington have effectively done more to bring Tehran to the table than any other measure because they prevented the regime from accessing the international financial system.