The United States and European Union announced Monday that they are easing economic sanctions on Iran. That would be reassuring if it meant Iran has really given up its pursuit of a nuclear arsenal.

But that would be naive.

The sanction loosening was prompted by the International Atomic Energy Agency’s report, issued earlier Monday, that Iran has stopped its enrichment of 20 percent uranium, a stepping stone on the march toward “weapons grade” material.

Though that conclusion from the United Nations’ agency sounds like good news, keep in mind that as the world’s top state sponsor of terrorism, the Iranian regime still falls far short of trustworthy status.

Iran reached an interim agreement on its nuclear program with six world powers (including the U.S.) in late November. The accord called for negotiations to continue.

At the time that deal was struck, Israeli Prime Minister Benjamin Netanyahu branded it a mistake of historic proportions. And even French Foreign Minister Laurent Fabius called it a “sucker’s deal.”

Like other critics, they insisted that easing sanctions will make it easier for Iran to surreptitiously persist in its long-term aim to develop nuclear weapons.

So before President Barack Obama places too much faith in the radical Islamic mullahs who run Iran, he would do well to ponder advice from a predecessor who engaged in successful arms control negotiations of his own.

George Schultz served Ronald Reagan admirably as Secretary of State. Two months ago in a guest column for The Wall Street Journal, Mr. Schultz recalled that his boss had some very clear views on negotiation strategy, concluding with this astute observation:

“The guy who is anxious for a deal will get his head handed to him.”

And Obama administration officials should keep their heads when negotiating with Iran.