Iran has the capacity to build a nuclear weapon, but its leadership “has not yet decided to build or demonstrate the bomb” and “therefore our [U.S.] focus should be on convincing them not to flip the bomb-production switch.”

That’s advice from Siegfried Hecker, director of the Los Alamos National Laboratory from 1986 to 1997.

He offered his insight in an interview on the Geneva P5 plus 1 interim agreement with Iran that was published Wednesday by Stanford University’s Center for International Security and Cooperation (CISAC).

Hecker added, “Completely getting rid of the [Iranian] bomb option is not possible through military action or sanctions with political pressure. The only chance is through diplomatic means.”

His is a little-publicized view, and one I share: that what brought Iran to the table was not just tough economic sanctions, but also that the Tehran regime has reached its desired nuclear capabilities — and now is ready to negotiate.

This is a tough-minded view. What’s unrealistic is that more sanctions can force Iran to give up its program to enrich uranium altogether. A House Foreign Affairs Committee report, released July 30 in support of a tougher Iranian sanctions bill that passed the House 400 to 20 the next day, notes, “Notwithstanding the costs imposed on Iran by the sanctions to date, Tehran continues to make rapid progress on its nuclear weapons program.”

So why listen to Hecker?

First, he has spent the past 20 years working with Russian nuclear laboratories to secure that country’s nuclear materials. More recently he has focused on nuclear activities in India, Pakistan, Iran and North Korea. In 2010, Hecker and two colleagues were invited to be the first Americans to visit North Korea’s secret uranium enrichment facility at Yongbyon.

In a Nov. 20, 2010, CISAC report, Hecker said that the facilities he saw “appear to be designed primarily for civilian nuclear power, not to boost North Korea’s military capability. . . . Nevertheless, the uranium enrichment facilities could be readily converted to produce highly-enriched uranium (HEU) bomb fuel (or parallel facilities could exist elsewhere).”

Hecker also has been involved in the so-called Track II diplomacy with Tehran. He was among a U.S. group that met with Iranian Foreign Minister Mohammad Javad Zarif and his diplomatic team in September, after the United Nations General Assembly session. The team included nuclear specialists.

Iran, Hecker said, has done “most of the work necessary to build nuclear weapons,” meaning researching the arming devices and delivery vehicles. He believes this in part because Tehran “has not satisfactorily explained nor given access to work and sites suspected of past nuclear weapons-related activities.”

Hecker is talking about Parchin, a military complex 18 miles southeast of Tehran where, according to a 2011 International Atomic Energy Agency report, there were high-explosive and hydrodynamic tests that could have been related to nuclear weapons. IAEA inspectors haven’t had access to Parchin over the past two years.

Hecker said he believes that “Iran’s extensive missile development and testing program also points to Tehran pursuing the option of missile-deliverable nuclear weapons.”

The only thing needed up to now has been the capacity to build enough weapons-grade uranium, which, Hecker said, “I believe they now have.”

So what’s his suggestion to freeze the program?

“We need to make it clear to the Iranian regime [leaders] that they are better off without pursuing the bomb. This will take time,” he said.

And what’s going to bring those leaders around?

Hecker says that “if Iran wants nuclear energy and relations with the West, I believe we need nuclear integration, no isolation, such as those peaceful programs in South Korea and Japan.”

That means living with a nuclear-capable Iran whose enrichment program is limited to a grade of 5 percent for generating power or research and sharply reducing to below 5,000 its number of centrifuges, which do the enrichment. All this must be open to continuous IAEA inspection. In short, trust but verify.

Whether this can be accomplished in the upcoming negotiations remains to be seen.

What’s not going to happen is Iran ending its nuclear program because of sanctions.

The stated goal of the Nuclear Iran Prevention Act of 2013, passed in the House and pending in the Senate, is “to compel the Government of Iran to verifiably suspend, and ultimately dismantle, its weapons-applicable nuclear program, including, but not limited to, the cessation of all uranium enrichment and plutonium-related activities,” according to the House Foreign Affairs Committee report on the legislation. It is doubtful the House bill will come up for a vote in the Senate, since a bipartisan Senate group seeking to pass additional sanctions to bolster the U.S. position in the upcoming Iran negotiations does not go that far.

However, the basic issue of Iran having a nuclear complex with the ability to enrich uranium is implicit in the Geneva interim agreement signed Nov. 24. It said the still-to-be-negotiated comprehensive solution “would involve a mutually defined enrichment program with practical limits and transparency measures to ensure the peaceful nature of the program.”

The solution may be in what then-Secretary of State Hillary Rodham Clinton told the BBC in an interview on Dec. 3, 2010: “They [the Iranians] can enrich uranium at some future date once they have demonstrated that they can do so in a responsible manner in accordance with international obligations.”

For previous columns, go to