In 2003, the United States initiated perhaps the greatest strategic disaster in US history by diverting attention from a necessary war in Afghanistan to an unnecessary war in Iraq. The Iraq war resulted in hundreds of thousands dead and wounded, untold economic catastrophe, states in the Middle East in complete ruin, and the rise of Isis – all while the effort to go after terrorists in Afghanistan languished.

President Donald Trump’s first speech before the United Nations general assembly this week made clear that Trump wants to take America down a similar path by diverting much-needed attention from North Korea to starting an unnecessary conflict with Iran.

If the United States and the world cannot convince Trump to support the Iran nuclear deal and instead focus on real problems, America may once again plunge into a violent disaster in the Middle East, and in the process damage efforts to deal with a country that already has nuclear weapons.

The threat from North Korea is real, and Trump used his speech to outline the need for an international pressure campaign against Kim Jong-un. There is little disagreement on the need for a tough stance against North Korea, as evidenced by the UN security council’s recent unanimous vote to impose new sanctions.

But Trump is having a difficult time implementing a coherent strategy on North Korea. He has picked a fight with America’s South Korean ally, whose support is essential. He frequently hurls hyperbolic rhetoric, raising the chances of miscalculation that could lead to conflict. And he talks as though war is inevitable, a theme he reiterated before the world’s leaders when he said, “Rocket Man [Kim Jong-un] is on a suicide mission for himself and his regime.”

Significant challenges remain in dealing with North Korea, even if Trump can get his own act together. China is unwilling to apply maximum pressure on North Korea for fear Pyongyang will collapse. Enforcing sanctions elsewhere is often like putting fingers in a dam full of leaks. It’s unclear what kind of a diplomatic deal the United States wants with North Korea. And little seems capable of convincing Kim Jong-un that he will be safe without nuclear weapons.

With obstacles this great, Trump should be providing leadership in pursuing an effective international strategy to deter North Korea, reassure US allies, add sanctions pressure, and engage in real diplomacy.

Instead, Trump is looking to rip up the deal that is currently preventing Iran from developing a nuclear weapon. If he succeeds in doing so, he will help turn Iran into the next North Korea and ratchet up the chances of conflict.

The deal prevents Iran from getting a nuclear weapon for years. UN inspectors have verified that Iran is complying with the terms of the deal. Even Trump’s administration has certified twice that Iran is living up to its end of the bargain. Moreover, the world backs the deal, with Russia, China and Europe all helping to enforce it.

If an Iran-style nuclear deal had been on the table at any point with North Korea, the United States would have jumped at the opportunity (and in fact came very close to making the Agreed Framework deal with North Korea work in the 1990s). Tearing up the Iran deal would be the strategic equivalent of shooting oneself in the foot.

But that’s exactly what Trump seems to want. In his UN speech, Trump placed the Iran nuclear deal in his sights: “The Iran deal was one of the worst and most one-sided transactions the United States has ever entered into. Frankly, that deal is an embarrassment to the United States, and I don’t think you’ve heard the last of it. Believe me.” Recent reports back up this message that Trump intends to rip up the deal, and the US ambassador to the UN, Nikki Haley, almost said as much in a recent speech on Iran.

It’s hard to overstate the potential disaster of destroying the Iran deal. Iran would be incentivized to race to get a nuclear weapon. The partners that helped make the Iran deal happen – Europe, China, Russia – would leave the US behind and continue doing business with Iran, making impossible any renewal of international pressure. And if Iran actually acquired a nuclear weapon, it could embolden Iran to escalate its regional provocations. All of this would result in more confrontation with the United States, and greater chances of war.

In fact, withdrawing from the Iran nuclear deal would undermine Trump’s efforts to convince the world that he is looking for a diplomatic solution with North Korea: if Trump is willing to rip up a deal preventing Iran from getting a nuclear weapon, why should anyone believe he’s willing to deal with North Korea? And why would North Korea deal with Trump if he doesn’t live up to US commitments?

In 2002, less than a year after invading Afghanistan, President George W Bush used his speech before the UN general assembly to make the case to the world for action against Iraq. Let’s hope, when history looks back on Trump’s first UN speech, it’s not viewed as the opening salvo in a completely preventable war with Iran.