The US government has publicized classified information detailing the location, design and specifications of a launch site to be built from this summer for Israel’s new Arrow 3 anti-ballistic missile system. The details, apparently spilled in error, appear to include highly sensitive information relevant to the struggle against Iran’s nuclear ambitions.

The material specifies, for instance, that the launch site must be completed by the end of next year, by which time, it says, Israel expects to have the Arrow 3 — a missile defense system crucial to Israel’s plans for countering an Iranian nuclear threat — operational.

News of the leak came as the Israeli official who oversees the Arrow 3 project revealed on Monday that Israel is speeding up the missile system’s development because of “the nuclear threat.”

The details were revealed, apparently inadvertently, in a tender issued by the US Federal Business Opportunities website inviting bids from American defense contractors to build the $25 million installation. The tender contains over 1,500 pages of information, and includes classified information specifying that the launch site will be built at what it says is the Israeli Air Force base at Tal Shahar. It features diagrams showing four concrete-hardened launchers, each designed to hold six rockets.

The tender also includes data on the underground depth of the launchers and the thickness of the concrete protection for the launchers, which is to be reinforced with steel mesh. The specifications also call for steel doors to protect against potential blast damage.

The faux pas was originally highlighted by Jane’s Defence Weekly, an established and widely cited military publication. Jane’s notes that while the spilled information does not name the missile system for which launch site is being built, it is “almost certainly for the new Arrow 3.”

Jane’s further reports that the Tal Shahar facility is already “the location of the IAF’s third Arrow 2 battery, which became operational in 2012.”

According to Jane’s, quoting from the tender, “Four new launcher buildings will be built on sites cut into the surrounding hills, each containing six interceptors in vertical launch positions and gantry cranes for erecting further missiles. It means Israel could potentially launch 24 Arrow 3 interceptors at an incoming wave of ballistic missiles and then engage any targets that were not successfully destroyed using its Arrow 2 interceptors.”

In detailing the specifics of the launch site’s protection, Jane’s also quotes the tender as noting that “the electrical components will be protected against the electro-magnetic pulse produced by a nuclear detonation.”

Companies seeking to build the facility were given until June 7 — Friday — to submit their bids, with the work set to begin on August 30. The successful contractor will have 485 days to complete the facility. “As such, the estimated completion date for the launcher facility would be around the end of 2014, which corresponds with Israel’s hope of making the Arrow 3 operational sometime in 2015,” Jane’s reported.

The Arrow 3, still under development, is designed to shoot down incoming ballistic missiles at ranges up to 2,500 kilometers (1,500 miles) and is Israel’s answer to the threat of an Iranian long-range rocket attack, potentially including nuclear-tipped missiles. The Arrow 3 is scheduled to be deployed by 2015.

Jane's diagram of Tel Shahar base

Jane’s diagram of Tal Shahar base

According to the tender, the complex is to be built at Tal Shahar, midway between Jerusalem and Ashdod. The sensitive details about the project have since been removed from the website where the tender was originally published.

Israeli officials say Israel seeks US assistance in building military installations despite the security risks because it prefers to work with seasoned contractors who have experience in the field. Reportedly, the US Army Corps of Engineering is currently overseeing the construction of a separate project, a $100 million underground complex for the Israeli Air Force just outside of Tel Aviv.

On Monday, Israel said it was speeding up its development of the Arrow 3. Col. Aviram Hasson, who heads the project, said it was being accelerated because of potential nuclear threats. “We want to reach a situation in which Israel has a ready defense for any threat, present or future,” Hasson said at a conference in Tel Aviv.