President Trump has not yet pulled America out of the 2015 Iran nuclear deal. But he just took a vital step toward doing so, in a landmark speech on Friday that in plain language dismantled the dangerous fictions on which the deal was built.

Chief among these fictions is the notion that a nuclear program in the hands of Iran’s predatory, terror-sponsoring Islamist regime could ever be “exclusively peaceful.” This was a phrase repeated endlessly by President Obama’s diplomatic team during the negotiating of the Iran nuclear deal, and it is enshrined in the final text, as if saying could make it so.

Iran has already given the lie to this fantasy, most prominently by continuing to test ballistic missiles. These are delivery vehicles that are only likely to be of use if Iran employs its “exclusively peaceful” nuclear program as cover to acquire nuclear warheads.

Citing the case of Iran’s longtime partner in missile proliferation, North Korea, Trump warned that it is folly to downplay Iran’s ambitions: “As we have seen in North Korea, the longer we ignore a threat, the more dangerous that threat becomes.”

Ensuring that Washington will now pay attention, Trump announced in his speech that he will not recertify that Iran is in compliance with the agreement. Under the Corker-Cardin law, passed in 2015 and officially dubbed the Iran Nuclear Agreement Review Act, this decertification kicks the problem to Congress, where lawmakers will have 60 days to come up with solutions.

It should help focus their minds that Trump stipulated: “In the event we are not able to reach a solution working with Congress and our allies, then the agreement will be terminated.” He noted that, as president, it is his prerogative to cancel America’s participation in this deal “at any time.”

Pulling America out of the deal would be the best course by far, and that is where any honest debate ought to end up. This signature foreign-policy agreement of President Obama, officially known as the Joint Comprehensive Plan of Action, or JCPOA, is a bargain so flawed that there is realistically no way to fix it. Haggled out with Iran by six world powers — Russia, China, France, Britain, Germany and the U.S. under Obama (in this instance leading from in front) — the JCPOA is thick with complexities that obscure the basic tradeoffs with which Obama enticed Iran to agree to this deal.

But there’s a simple bottom line. President Obama promised that on his watch Iran would not get nuclear weapons. Obama achieved this by cutting a deal that effectively paid off Iran upfront to delay a nuclear breakout until after he left office. He did this at the cost of greatly fortifying Iran’s predatory, Islamist regime, without ending its nuclear program. That is what Trump has inherited. As he accurately summed it up: “We got weak inspections in exchange for no more than a purely short-term and temporary delay in Iran’s path to nuclear weapons.”

The terms of this deal virtually ensure an Iranian nuclear breakout, on a scale and with a reach that will be even more dangerous when it comes. Without requiring any change in the nature of Iran’s terror-sponsoring regime, the deal dignified Tehran on the world stage, greatly eased global sanctions, allowed Iran access to more than $100 billion in frozen oil revenues, and topped that off with the related settlement from the U.S. of $1.7 billion, shipped secretly to Iran in cash.

The JCPOA also came crammed with sunset clauses, set to eliminate restrictions on everything from commercial-scale enrichment of uranium, to the design and launch of ballistic missiles “capable of carrying nuclear weapons.” It is also full of loopholes, such as the wording in which Iran is not required, but merely “called upon,” to stop developing nuclear-capable missiles.

To maneuver this unpopular deal past the American public and through the political mills of Washington, Obama’s White House skipped submitting it the Senate for ratification as a treaty — where it would almost certainly have been voted down.

Instead, Obama rushed the deal to the United Nations Security Council, where on July 20, 2015, six days after the final text was announced, it was approved as a set of annexes to Resolution 2231, before Congress had any chance to debate the substance (or discover, despite Obama’s promise of transparency to Congress, the secret side deals).

Directing U.S. foreign policy away from the perils and noxious commitments of this terrible deal is a daunting task. It is made all the more difficult because Iran’s oil-wealth is bait for lucrative business contracts — fueling the chorus from Europe in favor of the keeping the deal. And it is made yet more difficult by the lingering haze of talking-point narratives with which the Obama White House peddled this deal to the media, orchestrating the deal’s praises via the “echo chamber” bragged up early last year to the New York Times magazine by Obama’s former chief fabulist and deputy national security adviser for strategic communications, Ben Rhodes.

Trump, in trying to counter this debacle, has begun with the expedient of laying out the truth. In his speech on Friday, he began by detailing the core problem, which is not Iran’s nuclear program per se, but the character of Tehran’s regime — world’s leading state sponsor of terrorism — which, having seized power in 1979, “raided the wealth of one of the world’s oldest and most vibrant nations, and spread death, destruction, and chaos all around the globe.”

Trump clarified how the JCPOA “threw Iran’s dictatorship a political and economic lifeline,” noting that “Since the signing of the nuclear agreement, the regime’s dangerous aggression has only escalated.”  He listed a number of Iran’s specific violations of the deal, in letter and spirit, as grounds for decertifying compliance. He announced that his administration was imposing new sanctions on Iran’s Islamic Revolutionary Guard Corps, which he described, accurately, as “the Iranian Supreme Leader’s corrupt personal terror force and militia.”

None of this answers the question of what follows if America walks away from the Iran deal. But Trump has now opened the way to a robust debate, and begun clearing the road toward whatever it might genuinely take to avert the nightmare prospect of a Tehran regime armed with nuclear missiles. That’s a lot more promising for the security of America and its allies than relying — until it’s too late — on the sham of a rotten agreement annexed to a UN resolution.