The US government publicized classified information detailing the design and specifications of Israel’s Arrow 3 anti-ballistic missile system, including its location and the thickness of protected launch silos.

Details of the $25 million project were revealed in a tender for American defense contractors to build the installation. The tender contained over 1,500 pages of information, and included classified information such as diagrams showing four concrete-hardened launchers, each designed to hold six rockets.

The tender also included data on the underground depth of the launchers and the thickness of the concrete protection that was to be reinforced with steel mesh. The specifications also called for steel doors to protect against blast damage.

The faux pas was originally highlighted by Jane’s Defence Weekly, a longstanding and widely cited military publication.

The Arrow 3, still under development, is designed to shoot down incoming ballistic missiles at ranges up to 2,500 km (1,500) 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.

According to the tender, the complex is to be built at Tel Shahar, midway between Jerusalem and Ashdod, and is scheduled to be completed within a year and a half. The sensitive details about the project have since been removed from the website where the tender was published. The Israeli official would not say whether or not the plans had been modified as a result of the leak.

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