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President Barack Obama said on Wednesday that rejecting his administration’s nuclear deal with Iran would be a historic mistake — and he called it the most important foreign policy debate since the invasion of Iraq.

In a speech at American University in Washington, the president said that the Iran deal followed in the tradition of the decades of diplomacy that ended the Cold War without a single shot fired.

And he said that many of the critics of the deal are the same people who exaggerated intelligence and misled the country about the costs of the war in Iraq.

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The arguments are the same, he said — that Iran can't be handled with diplomacy, that military strikes don't have consequences, and that the United States shouldn't worry about the opinion of the rest of the world.

"But none of these arguments hold up," he said. "They didn't back in 2002 and 2003. They shouldn't now."

The president dismissed the arguments of “armchair nuclear scientists” opposed to the deal, which aims to stop Iran from building a nuclear weapon in exchange for the scaling back of economic sanctions.

He called it not just the best available option but "the strongest non-proliferation agreement ever negotiated.”

Some critics in Congress, which will vote on the deal next month, have said that the administration was hoodwinked. But Obama said that rejecting the deal would accelerate, not slow, Iran’s path to a nuclear bomb.

“So, in that sense, the critics are right,” he said. “Walk away from this agreement and you will get a better deal — for Iran.”

He encouraged Congress to set aside politics and consider the stakes of the vote.

"If Congress kills this deal," he said, "we will lose more than just constraints on Iran's nuclear program or the sanctions we have painstakingly built. We will have lost something more precious: America's credibility as a leader of diplomacy. America's credibility as the anchor of the international system."