WASHINGTON — The United States on Thursday formally began the process of activating a controversial snapback mechanism aimed at reimposing sanctions on Iran as US Secretary of State Mike Pompeo formally handed over a letter to the UN secretary-general despite opposition from Europe, China and Russia.

“The process to re-impose sanctions on Iran begins. Today I hand-delivered a letter to UN Security Council President Dian Triansyah Djani to formally notify the Council of something we all know too well — Iran's failure to meet its commitments under the terrible nuclear deal, Pompeo said in a tweet.

Expressing confidence over the success of the move, Pompeo said he was confident that the “sanctions would come back into effect in 30 days.”

“The United States will never allow the world’s largest sponsor of terrorism to buy and sell ... weapons,” Pompeo added.

Criticizing the UN Security Council for rejecting earlier this week the US resolution calling for the extension of the arms embargo on Iran, Pompeo said: "Make no mistake: the @UN Security Council failed to hold Iran accountable, enabled the world's top state sponsor of terrorism to buy and sell deadly weapons, and ignored the demands of countries in the Middle East. In New York today, America will correct these errors."

Justifying the US action, the secretary of state said: The prior administration left no doubt that the US has the ability to snap back sanctions on Iran. That's what we intend to do. As President @realDonaldTrump said, we will not continue down a path whose predictable end is more violence, terror, and a nuclear-armed Iran.

Reacting angrily to the US move, Iran warned of the dangerous consequences of the US push.

“The United States has no right to trigger the reimposition of all UN sanctions on Iran,” the Iranian foreign minister said in a letter to the United Nations, calling on members of its Security Council to reject Washington's move.

"The US push to reimpose UN sanctions on Iran will have dangerous consequences...Iran has exercised restraint in good faith...Now it is the international community's turn to counter the unlawful push by the United States," Mohammad Javad Zarif said in the letter.

Iranian state TV said the letter had been submitted to the head of the UN Security Council by Iran's UN envoy, Majid Takhteravanchi. — Agencies