The US will introduce a Security Council resolution next week to extend the UN arms embargo on Iran, Secretary of State Mike Pompeo said Wednesday.

The top diplomat told reporters at the State Department that the measure is "eminently reasonable," vowing "one way or another we will do the right thing."

"We will ensure the arms embargo is extended," he said amid opposition from China and Russia, two of the other veto-wielding permanent council members.

The embargo is set to expire Oct. 18 under the nuclear deal with Iran that Washington exited under US President Donald Trump.Pompeo said there are "nations lining up" to sell Iran weapons that will "destabilize the Middle East, put Israel at risk, put Europe at risk, risk American lives as well. We're not going to let it happen."

“The Security Council’s mission is to ensure international peace and security," said Pompeo. "The council would make an absolute mockery of that mission if it allowed the number state sponsor of terrorism to buy and sell weapons freely.”

One option the US could pursue in the event that either the measure fails to receive necessary support in the 15-member council, or if Russia or China exercise vetoes, is what is called "snapback."

That would entail triggering all sanctions lifted as part of the 2015 nuclear accord, an option Pompeo said the US is considering. 

"We're deeply aware that snapback is an option that's available to the United States, and we're going to do everything within America's power to ensure that that arms embargo is extended," he said. "I am confident that we will be successful."

Trump unilaterally pulled the US out the nuclear deal in 2018 above objections of all participants, and has gone on to reimpose sanctions the US lifted under the agreement, angering Iran, which retaliated by reneging on some of its commitments.

It is unclear if the US has standing to invoke snapback since it is no longer a party to the accord.