Iran will remain under the threat of renewed international sanctions for 15 years, according to a letter to the UN from the six countries that reached the accord with Tehran curtailing its nuclear program.
The 10-year agreement struck in Vienna this week calls for a lifting of the sanctions that have crippled the Iranian economy in exchange for measures to ensure Iran does not build nuclear weapons.
But the historic accord also features a "snapback" mechanism to restore the sanctions almost immediately if Iran does not live up to its commitments.
According to the letter, dated Tuesday and obtained by AFP, the so-called P5+1 countries -- US Security Council permanent members Britain, China, France, Russia and the United States, plus Germany -- commit to extending this mechanism by five years after the nuclear accord expires.
"For a period of five years following this termination," the letter says, the P5+1 countries will maintain the principle "that provides for the reinstatement of measures in the event of Iran's significant non-performance" of any of its commitments under the Vienna accord.
The presence of a "snapback" mechanism was known before now, but the timescale it covers had been unclear.
In coming days the Security Council is expected to pass a resolution endorsing the Vienna agreement and opening the way for the gradual and conditional lifting of sanctions against Iran.
