One danger Iran presents to the world is ideological, but the greatest threat it poses is nuclear. If Iran, a regime with ties to terrorism, were to develop weapons of mass destruction, then global security would be imperiled.

The United States recognizes the risks. That’s why President Trump is using sanctions to compel Iran to renegotiate the 2015 nuclear agreement. He saw the deal as too weak and too narrow. So how about America’s European allies who also were signatories: Where do they stand on strengthening the accord? For more than a year, we’ve supported U.S. calls for the United Kingdom, Germany and France to step up. They’ve equivocated – partly out of fear of confrontation, partly to maintain business relationships.

On Tuesday, however, those three countries finally made an important move against Iran. While the trio didn’t accede to Trump’s wishes and join the U.S. in withdrawing from the deal, they did take action: The Europeans warned Iran that it must abide by terms of the deal or face reinstatement of United Nations sanctions. This shifts Europe closer to the U.S. position and turns up the pressure on the mullahs in Tehran.

Why is Iran so dangerous? Iran has never stopped seeking to become a regional power through disruptive force and proxy attacks. It supports Hezbollah, the terrorist army based in Lebanon, and Shiite militias in Iraq. The nuclear deal, signed by then-President Barack Obama, sought to put a cap in the weapons bottle, but it contained sunset clauses on development and failed to address Iran’s support of terrorism and pursuit of ballistic missiles.

We reluctantly supported the 2015 deal, yet we see what Trump sees: a continual threat that must be addressed. We believe that with Europe’s help, the United States has the opportunity to bring Iran to heel and then support its growth as a peaceful state.

There’s plenty of reason to both mistrust Iran and seek a negotiated settlement with this menacing foe. U.S. sanctions have bitten hard. In response, Iran has been pulling away from the deal, which the Europeans still want to save – and now expand.

At the same time, Iranian aggression has been on the rise. Iran shot down a U.S. surveillance drone and is believed to be responsible for attacks on oil tankers moving through the Strait of Hormuz. After Iranian-backed militias organized violent demonstrations at the U.S. Embassy in Baghdad, Trump ordered a drone attack that killed Iranian Maj. Gen. Qassem Soleimani. He was commander of the Revolutionary Guards’ Quds Force and the master of Iranian mayhem.

Tensions between the U.S. and Iran appear to have cooled – at least temporarily. That gives the Europeans a window to start their own talks with Tehran, backed by the threat of sanctions. Technically, the Europeans initiated a dispute mechanism contained in the 2015 accord to force Iran back into compliance. But they also want to start negotiations over Iran’s missiles and regional adventurism.

British Prime Minister Boris Johnson took Trump’s side in a television interview Tuesday, supporting a full renegotiation of the nuclear agreement. “If we’re going to get rid of it, let’s replace it, and let’s replace it with the Trump deal,” Johnson said.

U.S. sanctions are punishing, but Europe is a lot closer to Iran and has its own economic ties. The U.K., Germany and France also remain committed to the nuclear deal.

The tougher Europe gets on Iran, the more likely it is the U.S. strategy will work.

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