Also, in 2006, the Iranian oil Minister, Kazem Vaziri-Hamaneh, claimed that Iran may use the oil weapon, if such would serve its national interests. (http://asianews.it/viewp.php?1=6550, dated 27 June 2006).
Also, the Iranian government spokesperson, Gholam-Hossein Elham said: "Iran would disrupt oil supplies as the last resort if it were punished over its nuclear program". (http://www.zaman.com).
“Obligation not to defeat the object and purpose of a treaty prior to its entry into force
A State is obliged to refrain from acts which would defeat the object and purpose of a treaty when:
(a) It has signed the treaty or has exchanged instruments constituting the treaty subject to ratification, acceptance or approval, until it shall have made its intention clear not to become a party to the treaty; or
(b) It has expressed its consent to be bound by the treaty, pending the entry into force of the treaty and provided that such entry into force is not unduly delayed.
Source: PhD BAhman Aghai Diba