The deal just struck by Iran, the United States and five other world powers in Vienna is a major victory for U.S. national security. It shrinks Iran's nuclear complex down to a token capability and wraps it in a permanent inspection and monitoring regime.
The new agreement doesn't overthrow the clerical regime ruling Iran. It doesn't change Iran's policies toward Israel or its Arab neighbors. And it doesn't force Iran to end the repression of its own people.
The agreement forged between Iran and the world's powers does only one thing, but it is a big one: It reverses and contains what most experts consider the greatest nuclear proliferation challenge in the world. Whatever else Iran may do in the world, it will not do it backed with the threat of a nuclear weapon.
U.S. negotiators went into the Iran talks with three key objectives: cut off all of Iran's pathways to a nuclear bomb, put in place a monitoring system to catch any Iranian cheating and keep together the global coalition that can snap back sanctions if Iran breaks the deal. After 22 months of hard bargaining they have emerged with that and more. This detailed 100-plus-page agreement dismantles much of Iran's nuclear program, freezes it and puts a camera on it.
The deal eliminates the three ways Iran could build a bomb.
First, without the deal, Iran could use its centrifuges to purify enough uranium for one or more bombs within weeks. These high-tech machines are the size and shape of water heaters but made of specialized metal alloys. They spin uranium gas at supersonic speeds, cascading the gas through assemblies of thousands of machines. When it reaches a purity level of about 5 percent, the gas can be turned into a powder form used to make fuel rods for nuclear reactors. Iran says that is all it wants to do — make fuel. The problem is that the same machines in the same facilities can keep going until the uranium is enriched to 90 percent purity. Then the gas can be turned into the metal core of a weapon. This deal blocks that path.
Iran has agreed to rip out over two-thirds of the 19,000 centrifuges it has installed. Just over 5,000 centrifuges will be allowed to continue enriching uranium. All will be located at one facility at Natanz. The deep underground facility at Fordow that so worried Israeli planners (since it could not be destroyed with their weapons) will be shrunk to a couple of hundred operating centrifuges — and these are prohibited from doing any uranium enrichment.
Furthermore, Iran cannot enrich any uranium above 3.67 percent. This limit lasts for 15 years.
Together, these cuts mean that even if Iran tried to renege on the agreement, it would take it at least a year to make enough uranium for one bomb — more than enough time to detect the effort and take economic, diplomatic or military steps to stop it. Uranium path, blocked.
Without the deal there is a second way Iran could make a bomb — with plutonium. The bomb at Hiroshima was made of uranium; the bomb at Nagasaki was made of plutonium. Unlike uranium, plutonium does not exist in nature. It is made inside nuclear reactors, as part of the fission process, and then extracted from the spent fuel rods. Iran is constructing a research reactor at Arak that would have produced about 8 kilograms of plutonium each year, or enough theoretically for about two bombs.
Under the new deal, Iran has agreed to completely reconfigure the Arak reactor so that it will produce less than 1 kilogram a year. The old core will be shipped out of the country. Further, Iran has agreed to never build facilities that could reprocess fuel rods and all spent fuel will be shipped out the country. Plutonium path, blocked.
Finally, without the deal Iran could try to build a covert facility where it could secretly enrich uranium. The verification and monitoring system required by this deal makes that all but impossible. Covert path, blocked.
This agreement, however, does leave Iran with significant capabilities. It would be better if the entire nuclear complex was razed to the ground and the earth salted so it could never be rebuilt.
But we are not Rome and Iran is not Carthage. Such a deal was the preferred option of most nonproliferation experts, including myself, 12 years ago when Iran's enrichment program was first disclosed. But the Bush administration rejected talks with Iran, when it had only a few dozen centrifuges. "We don't negotiate with evil," said Vice President Dick Cheney, "we defeat it." That strategy failed.
This final comprehensive agreement is cleverly crafted so that all sides can claim victory. Iran can say with pride that its rights have been recognized, that sanctions will be lifted and that it will not destroy a single nuclear facility. And it will be correct. The beauty of this agreement is that Iran gets to keep its buildings and we get to take out all the furniture.
These terms effectively freeze the program for longer than it has been in full operation. It will shrink and confine Iran's nuclear work for a generation. A lot of change can happen in a generation. This deal gives us the best possible chance to influence the direction of that change.
Joe Cirincione is president of Ploughshares Fund and author of "Nuclear Nightmares: Securing the World Before It Is Too Late." © 2015 Slate