The largest and most advanced deployment of antiballistic-missile assets in the region was the central feature of Operation Juniper Cobra, the biennial military exercise conducted by Israel and the U.S. Experts say this year's operation, which ran from Oct. 12-16, was designed to test the countries' joint ballistic missile defense (BMD) capabilities and send a message of deterrence to Iran, Syria and Hezbollah.

Iran, in fact, held war games of its own shortly before Juniper Cobra, which included firing missiles that could reportedly hit Israel.

The Juniper Cobra exercise involved units of the Israel Defense Forces (IDF), U.S. European Command and U.S. Missile Defense Agency. Among the assets tested were four defense systems designed to intercept ballistic missiles, such as those Israeli military and political leaders warn could eventually be deployed by Iran.

One objective was to assess the interoperability of Israel's Arrow-2 theater BMD system with three of the most advanced American systems: Thaad (Terminal High-Altitude Area Defense), which can reportedly reach altitudes of 93 mi.; the lower-altitude (50,000-ft. ceiling) PAC-3 (Patriot Advanced Capability) missile, an earlier version of which was deployed in Israel during Operation Desert Storm in 1991; and the sea-based Aegis BMD system.

Thaad and the PAC-3 are designed for terminal-phase BMD. Thaad works in conjunction with PAC-3 to conduct intercepts in the late descent and early terminal phase of an incoming missile, essentially creating overlapping coverage. Israel wants to integrate its Arrow-2 missile system with PAC-3 batteries to broaden the defensive shield.

The Aegis Standard Missile-3 (SM-3) system used in the exercise is probably the most operationally proven and capable of all American BMD technologies. The SM-3 is deployed on upgraded guided missile cruisers and destroyers, and is capable of missile-ascent and descent-phase intercepts.

Two Aegis-equipped destroyers, the USS O'Kane and USS Hopper, were among participants in Juniper Cobra. The USS Hopper successfully conducted an intercept of a sub-scale, short-range ballistic missile in the Pacific on July 30, during an exercise called Stellar Avenger. Hopper and two other destroyers--the O'Kane and USS Lake Erie--detected and tracked the missile, which was launched from Hawaii, with AN/SPY-1 radars that are part of the Aegis system. Hopper fired an SM-3 Block IA missile and guided it to hit the target 100 mi. overhead. The O'Kane conducted a simulated intercept, and the Lake Erie tracked the target. The hit was the 19th successful intercept for the Aegis system in 23 firings at sea.

The capabilities of at-sea intercepts are crucial, since one leg of a joint U.S.-Israel missile-defense program could be the stationing of Aegis cruisers in the Mediterranean and Red seas, where they would extend and enhance Israel's defensive umbrella.

Another major factor in missile-defense capabilities is the AN/TPY-2/TPSX forward-based X-band transportable radar, deployed by the U.S. (and manned by American personnel) in October 2008 at Israel's Nevatim air base in the Negev. The radar, one of the most advanced, was also expected to play a key role in the Juniper Cobra exercise.

Senior Israeli defense officials commenting on the exercise said Juniper Cobra 2009 was aimed at creating a joint communications infrastructure in case Israel is attacked and Washington decides to send the Aegis or Thaad systems to bolster the Arrow-2 BMD.