In return, the United States has agreed to begin withdrawing its economic sanctions against Iran in a little less than a year if it meets the terms of the agreement — the critical reward for a country whose economy has been crippled by them.

But critics of the deal have plenty of reasons to distrust Iran, which the State Department says is the world’s “most active state sponsor of terrorism” — arming terrorist militias across the Middle East, including Iraq, Syria and Yemen.

In Yemen alone, whose government has been toppled by rebel forces, Iran has been providing ethnic Houthis, a Shiite sect, with weapons, training and financing. After toppling the U.S.-backed government of President Abed Rabbo Mansour Hadi last month, the Houthis have seized control of major areas of Yemeni territory.

Iran’s goal: to install an Iranian client state in Yemen that the Saudis fear would threaten their country’s national security. The long unprotected border between Yemen and Saudi Arabia shows how likely that scenario has become as the war rages there, and that could easily explode into a broader regional conflict.

Let’s not kid ourselves about Iran’s goals. It already has effective control over several Middle Eastern capitals. Its Shia militant proxies are spreading throughout the region, stoking fears not only of the Saudis, but also in Egypt, Qatar, the United Emirates and others.

This is what triggered the Saudi air war in Yemen, joined by other Arab states, who are now contemplating sending ground forces across its border.

Iran is a central aggressor in this widening war, feared and distrusted by its Arab neighbors who are under no illusion about its territorial ambitions.

Yet incomprehensibly, Mr. Obama naively believes he can deal with Tehran and, even worse, can trust them to abide by this agreement.

With less than two years left in his presidency, and his job approval polls locked in the upper-40 percent range, Mr. Obama is looking to improve his troubled foreign policy legacy. He thinks the deal reached with Iran will do that.

But what if Iran is playing a cat-and-mouse waiting game in order to win suspension of the economic sanctions for a period of time? What if it reduces some of its centrifuges in the short run, but secretly continues enough uranium enrichment and other behind-the-scenes work to develop a nuclear weapon?

What is there in Iran’s behavior that makes the Obama administration so sure it can trust the Iranians to open all of its facilities to the International Atomic Energy Agency’s inspectors? Or in Ayatollah Khamenei’s sinister record of arming terrorist armies throughout the Middle East?

More than anything, Iran wants to lift the economic sanctions that will unlock capital resources to further arm, train and finance its proxies in the Arab world. That, after all, was the reward that greased the deal for them.

“The political understanding with details that we have reached is a solid foundation for the good deal we are seeking,” Mr. Kerry announced last week.

How can Mr. Kerry be so sure? As they say, the devil is in the details.

But also in the framework, too, says Senate Foreign Relations Committee Chairman Bob Corker of Tennessee, who expressed deep skepticism about multiple “red flags” in the agreement on Fox News Sunday. Among them are concerns about the kind of iron-clad, verifiable factors that would need to be met before the international sanctions would be lifted.

“There’s a lot of water that needs to go under the bridge here. Many, many details are unknown at this point,” he said.

Israeli Prime Minister Benjamin Netanyahu called the agreement “a historically bad deal,” adding that it was “a dream deal for Iran and a nightmare deal for the world.”

The world has become a much more dangerous place in the Age of Terrorism. For extremist groups such as al Qaeda in the Arabian Peninsula and the Islamic State, the chief target, outside of the Middle East, is America.

It would be the height of irresponsibility for Mr. Obama to ignore Iran’s malevolent ambitions in the Middle East for the sake of a legacy-building deal.

Iran has never hidden its hatred toward Israel. But the question we need to ask now is whether that hatred is so intense that it would conceal the development of a nuclear weapon.

• Donald Lambro is a syndicated columnist and contributor to The Washington Times.