Iran's Nuclear Programme

Iran is using a threat of developing a nuclear missile as a bargaining chip with the US to alleviate economic sanctions.
Scott Ritter makes the point essentially, that it would be better for Iran not to have a nuclear weapon. Being a nuclear threshold state means Iran isn't protected by a nuclear weapon, but it does however tempt the US and Israel to attack them with nukes to prevent Iran from having the opportunity to decide to have nuclear weapons.
Perhaps Iran took the "middle road" of being a nuclear threshold state for reason of internal political division within Iran, about whether Iran should have a nuclear missile programme. Clearly, the Ayatollah, the religious leader of Iran is against Iran having a nuclear weapon.