Gary Milhollin is director of the Wisconsin Project on Nuclear Arms Control, which monitors weapons proliferation. He spoke with State Department correspondent Martin Sieff
Question: How significant is the Russian contribution in professional expertise and equipment to Iran's nuclear and missile development programs?
Answer: What the Russians are providing is so important that it can cause by itself a major shift in the Middle East strategic balance of power. If the Iranians are able to produce in a short period of time a large number of missiles with significant range thanks to this aid, they will have the capability to put nuclear warheads as well as conventional ones upon them.
Q: If Iran fails - or is prevented - from developing its own nuclear weapons, will that negate the threat it had hoped to pose with its missiles?
A: Even with conventional warheads only, the possession of such a missile force will give the Iranians a capability that neither they nor any other Middle East radical state has ever had before.
The implications for pro-American states in the region are serious. But the implications for the state of Israel are even more alarming.
Israel is a small country. Its population is very heavily concentrated in the coastal region and in and around Tel Aviv. Therefore, the prospect of hundreds of missiles armed even with conventional warheads falling on the country's main population center is an extremely serious one.
Q: Skeptics about the scale of that threat counter that Israel suffered virtually no casualties from the Scud missile bombardment by Iraq against Tel Aviv at the start of the  Persian Gulf war. Is this an accurate assessment of the Iranian conventional threat, too?
A: No. That kind of argument fails to consider the formidable capabilities now available in so-called "conventional" warheads. They have been getting far more powerful. Options now available include submunitions warheads and fuel-air explosives.
Submunitions warheads spray out hundreds of small but powerful bomblets over a wide area when they explode. The …