The new WikiLeaks documents show that Iran has been hunting for missile technology all over the world, seeking to buy gyroscopes, jet vanes and metals, and perhaps whole missiles from North Korea. But Iran also has experienced great difficulty building longer range missiles. Why? Some clues can be found in one of the most interesting documents just released, a briefing that Russian officials gave their American counterparts on Iran's progress, or lack of it.

A summary of the Dec. 22, 2009 meeting was marked "secret" but tumbled out on Sunday in the reams of memos released by WikiLeaks and major news organizations. Fourteen Russian and 15 U.S. government officials compared notes that day about missile threats from Iran and North Korea.

Judging by the summary, it was a lively back and forth, during which the Russians claimed the threat from Iran's missiles is not as great as some have predicted in the United States. The size and nature of the threat is important because it undergirds the U.S. plans for a multi-billion dollar ballistic missile defense system.

The Russians were prepared to talk "seriously" with the U.S. group, the summary says. Their message was Iran is struggling to lengthen the range of missiles that could carry heavy loads, such as a one-ton nuclear warhead, that might threaten the region or beyond. The Russians said their basic conclusion is that "Iran's ballistic missile program continues to be directed toward developing combat ready missiles to address regional concerns," not targets like the United States.

This was also the assessment made in May by the International Institute of Strategic Studies.

In the December meeting, there was a sharp disagreement about the U.S. claim that North Korea sold to Iran a batch of 19 missiles, known as the BM-25. The transfer was first reported publicly in 2006; the BM-25 missile is supposedly based on a Soviet naval ballistic missile design, the R-27, known in the West as the SS-N-6. This missile was first developed in the 1960s and later modernized; it was in service in the Soviet Union until 1988. Iran has not tested any of the missiles it imported. The U.S. officials speculated that Iran may have purchased it to reverse-engineer the technology (although North Korea has been known to ship parts, expertise and manufacturing facilities as well as the missiles themselves.) The U.S. officials said photos of the Iranian space launch rocket, the Safir, show an engine which looks like the one on the R-27, as well as fuel tanks and welds that resemble it. The U.S. officials said they had received "direct evidence" of the missile transfer from North Korea to Iran.

But the Russians strongly dismissed the BM-25 as a mirage, according to the summary. They said Iran would not have purchased an untested missile, and they doubted whether it even existed. "For Russia, the BM-25 is a mysterious missile," the summary says. "Russia does not think the BM-25 exists." They asked why North Korea would sell an untested missile; the Americans responded: for cash.

Both the Russians and Americans acknowledged the limitations of Iran's older, liquid-fueled missiles, based on the Soviet Scud and its modifications, including the Shahab-1, Shahab-2 and Shahab-3. Both sides also seemed to agree that the Safir is not a military threat because of the small size of the payload.

The key issue is Iran's pursuit of more modern and powerful solid-fuel missiles that could hit medium-range targets, such as those in the Middle East or Europe. Iran has been working on such a missile, called the Sajjil-2, which it has flight tested. (See my earlier post about it.) In the meeting, U.S. officials were more worried about this than the Russians, who said Iran continues to stumble with solid fuel technology. "In Russia's view, Iran appears to be having very serious problems with engine development," the summary says. U.S. officials countered that Iran has a decade of experience with short-range missiles using solid fuel, importing equipment from China, and could now extend it to larger missiles.

The Russians said Iran was a long way from building intercontinental ballistic missiles that could hit the United States. "Russia said its bottom line is that Iran lacks appropriate structural materials for long-range systems, such as high quality aluminum," the summary says. "Iran can build prototypes, but in order to be a threat to the U.S. or Russia, Iran needs to produce missiles in mass quantities, and it lacks materials sufficient for the type of mass production needed to be a security threat. Russia further noted that the technology for longer-range missiles is sophisticated and difficult to master."

At another point, the Russians said they think the North Koreans are working on a new, 100-ton capacity rocket engine using older technology, clustering the motors or stacking them. But Russia said the technology hasn't been actually spotted.