He added that the Iranian delegation chose not to accept our terms, despite the US clearly outlining its red lines, particularly an ironclad commitment from Tehran to abandon any nuclear weapons development or a quick path to one.

Vance said the US delegation will leave Islamabad after presenting a "final and best offer", with the main sticking point being Iran’s nuclear programme.

The US delegation left Islamabad after presenting Iran its "final and best offer", with the main sticking point being Tehran’s nuclear programme.