A U.S.-supplied missile shield to protect Gulf nations against Iranian attacks will take years to complete, requiring a step-up in regional trust, more U.S. sales of sensitive weapons, and intensive U.S. training to avoid mishaps in the volatile region.

The system would use U.S. early-warning satellites and a mix of U.S. and Gulf radars to detect the launch of an enemy missile and fire a ground- or sea-based missile to destroy it far above the earth.

The Gulf countries are upgrading their existing Raytheon Patriot systems to incorporate new PAC-3 missiles built by Raytheon and Lockheed Martin Corp., and are starting to buy wider-area and longer-range systems like the Terminal High Altitude Area Defense, built by Lockheed.

Washington has balked at selling a land-based Aegis combat system to deal with missile threats and any associated SM-3 missiles to Gulf countries, largely because such a system would be best suited to dealing with threats outside the earth's atmosphere that are beyond Iran's capability, Cordesman said.

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