To defend against cyberattacks, the Iranian government has begun installing a network that is separate from the Internet to better control information flow, according to a report by the University of Pennsylvania's Center for Global Communications Studies. Critical government and military agencies are expected to be on the network by the end of the month, according to the Washington Post. Project researchers say they already have evidence of a filtering capability. The technology is provided by China's Huawei corporation, the investigation finds.

“But it's a fencing match [that is standard in the world of electronic warfare],” the U.S. specialist says. “Now that they know our secret sauce [with discovery of the Stuxnet and Flame cyberintrusions], they've made it much harder to do.”

So if the path for nonkinetic, cyberattacks is blocked by new technology, what could the U.S. and Israel do to slow Iran's progress?

“Kinetic attack [with aerial bombs or other explosives] is one of the few options left, but you need a lot of critical information to make an air attack on a deeply buried target work,” says a senior U.S. Air Force official.

Some of those options are already in play. On Sept. 17, Fereydoun Abbasi, Iran's vice president and nuclear energy agency chief, said the electrical transmission lines between Qom and the Fordow nuclear enrichment facility (buried under a mountain) were severed with explosives, as were the power lines leading to the country's other underground enrichment facility at Natanz.

So far, Western justification for attacking Iran's nuclear development and delivery programs has been associated with the need to stop those efforts or create long delays. The goal is to ensure that sufficient enriched uranium cannot be processed to make nuclear weapons that could be delivered by missiles or even by trucks. Once the weapons are assembled and armed, they are difficult to keep track of, even by those who possess them.

Deputy Defense Secretary Ashton Carter, for example, was once part of a program to control chemical and biological weapons by making audits of what actually existed and where.

“The investigators found out that not even the senior Soviet leaders knew what they had or where it was hidden,” the U.S. specialist says. “Nuclear materials are the same. If Iran wanted to, it could get all the enriched uranium it wanted on the black market. If it wanted to focus solely on possessing a bomb, it could buy one.”

The technology to create effects against a truly deep underground facility, short of a nuclear weapon, does not exist. “We keep inventing and improving penetrating bombs,” says the U.S. defense specialist. “We've hardened them and we've boosted them and we've only increased the amount of the deeply buried target set we can defeat by a fraction. And right now the Israeli capability against deeply buried targets is not much more than a noise-level effect.”

As a result, the enthusiasm for a U.S. attack on Iran is negligible, and the technological ability for Israel to create the necessary effects is not much greater.