Iran’s linked development of nuclear energy and surface-to-surface missiles is motivating multiple missile-defense programs, including most of Israel’s work, exports of Patriot PAC-3 and Terminal High Altitude Area Defense missiles to the Middle East, and U.S. deployment of elements of the European Phased Adaptive Approach missile defense system. The progress of Iran’s projects, however, remains under debate and wrapped in secrecy. 

The Obama administration has led efforts by the P5+1 group (U.S., Russia, China, France and Britain—the permanent members of the United Nations Security Council—plus Germany) to negotiate agreements that confine Iran’s nuclear program to civil uses and provide assurance against covert or overt breakouts from such restrictions. Optimists see the current slump in oil prices putting pressure on Iran to pursue an agreement to lift sanctions. 

Some see a nuclear agreement as sufficient to contain Iran’s missile program. Medium- and intermediate-range ballistic missiles are mainly nuisance weapons because of poor accuracy and high cost, unless combined with weapons of mass destruction (WMD) payloads. They are ineffective against most military targets and, given the tracking, prediction and communications technologies available, a civil defense system can eliminate many casualties without forcing an entire city to take shelter. 

Others, however, see risk in two areas. One is that Iran may see the P5+1 process as a stalling tactic, and wait for the consensus on sanctions to erode. The other is that Iran might add guidance systems to its weapons, making them lethal and effective against more targets.

Sanctions were imposed because of an “unprecedented and inherently ephemeral set of circumstances,” notes Suzanne Maloney, senior fellow at the Brookings Institution. These include the inflammatory rhetoric of then-President Mahmoud Ahmadinejad and domestic repression.

In Mahoney’s view, “for months, Iran’s diplomacy has been focused on ensuring that Washington is seen as the spoiler if . . . prospects for a deal . . -.  go south.” She suggests the obstacle is simple: Iran’s supreme leader, Ayatollah Ali Khamenei, is not interested in any agreement that does not leave the nation’s nuclear capabilities intact.

Even if there are successes in negotiations or failures in Iran’s nuclear program, there is evidence that progress in missile development continues. In a presentation last year, Israeli missile-defense pioneer Uzi Rubin argued that indicators pointing to slowdowns in missile development, which some analysts see as the result of sanctions, may be misleading. Rubin cited ongoing if unsuccessful space-launch attempts and the May 2013 unveiling of a transporter-erector-launcher (TEL) for the 2,000-km-range (1,245-mi.) Shahab-3 missile. The TEL was not a prototype: Iran showed a production line, and modifications to the unit’s design disguise it as a civilian tractor-trailer. 

Other developments include Iran’s announcement in February 2014 of a multiple reentry vehicle (MRV) payload for the Shahab-3. The following month, Iran’s Fars news agency announced that the Shahab and the newer 800-km-range Qiam were equipped with MRVs, and showed images of 24 Qiams, apparently in a tunnel, and 44 weapons in a hangar. Also recently unveiled was Kadr F, which is capable of covering 1,950 km. Rather than a slowdown, Rubin says tests are being concealed as “part of a wider diplomatic effort to ease . . . sanctions.”

Rubin also warns of progress in adding GPS guidance to missiles. An October 2014 report by the Center for Strategic and International Studies (CSIS) quotes him as saying Iran added a guidance system to the 210-km-range, 600-kg (1,320-lb.) Zelzal-2 warhead and could do the same with longer-range missiles. “This threat can degrade the [Israeli military’s] ground capabilities,” Rubin says. “It can paralyze Israel’s war economy . . . and . . . inflict massive casualties.” 

Rubin says nations such as Iran find missile development easier and cheaper than building or maintaining strike aircraft. In a 2013 interview, he noted that “we are in the middle of a revolution” in guided rocketry. “An iPad can guide a missile,” he said, predicting a widespread increase in the use of guided ballistic missiles in the next five years.

Others are more cautious. The CSIS report pointed to areas of uncertainty, including “limited tests under ‘white- suit’ conditions” that give a distorted impression of accuracy and lethality, the potential effectiveness of missile defense systems, and the risks and costs of retaliatory strikes. Even with guidance systems that offer better theoretical circular-error-probable numbers, “CEP applies to 50% of perfectly located and launched missiles that operate perfectly in flight to reach a perfectly located target . . . [P]ractical test and evaluation, as well as U.S. combat experience warn that the error budget of things that can degrade operational accuracy in a real world missile is far greater than the accuracy of the platform would suggest.”