President Donald Trump’s reckless obsession with overturning former President Barack Obama’s policies will reportedly soon lead to him declining to certify the Iran nuclear agreement. If so, that would send the issue to Congress, which must not let the accord unravel.

Iran is living up to the deal. That’s the opinion of the International Atomic Energy Agency, tasked with verifying compliance. That’s the opinion of every signatory — adversary and ally alike — that was party to the multinational pact. And that’s the opinion of Trump’s top national security official, Secretary of Defense Jim Mattis, and top diplomat, Secretary of State Rex Tillerson.

So there is no technical breach of the deal — known formally as the Joint Comprehensive Plan of Action, or JCPOA. Instead, Trump may justify his decision by saying that the deal is not in the national security interest of the U.S. and that Iran has violated the “spirit” of the deal by its support of Hezbollah and Syrian President Bashar Assad, as well as for its ballistic missile program, among other issues.

Iran’s behavior is indeed bellicose and destabilizing. Which is exactly why it would be tragic if the theocracy were to develop nuclear weapons — the very issue the JCPOA is designed, and verified, to prevent.

The Iran deal is in the national interest, Dennis Ross, a longtime U.S. envoy to the Mideast, told an editorial writer. “To be fair, I do think something needs to be done about Iran’s behavior,” said Ross, now a distinguished fellow at the Washington Institute for Near East Policy. He added, “Don’t make the JCPOA a substitute for a strategy toward Iran; it should be an element of a strategy toward Iran.”

If Congress were to issue new sanctions on the nuclear issue, Iran would interpret that as breaking the agreement. That might lead Iranian hard-liners to push for a sprint to develop a nuclear weapon.

As important, it may be similarly interpreted by the other parties to the deal, who are highly unlikely to follow America’s radical action. Indeed, even British Prime Minister Theresa May — guardian of the “special relationship” between the United States and the United Kingdom — has publicly urged the U.S. to adhere to the deal, which she says is “vitally important for regional security.”

It’s also vitally important for geopolitical security.

If the U.S. reneges on a deal that Iran is complying with, every nation will rightfully question America’s word. For free-trade agreements such as NAFTA, that creates difficulties. For a potential deal with North Korea to contain the nuclear crisis, it creates danger.

The Iran deal “was a remarkable diplomatic achievement. It has dramatically reduced Iran’s capabilities to acquire nuclear weapons now or in the future,” Mark Bell, an assistant professor of political science at the University of Minnesota, told an editorial writer.

Congress should concur, and stand up for the deal itself as well as for multilateral approaches to global crises.