Fledgling US missile shield largely unproven

WASHINGTON, June 17 (Reuters) Reports that North Korea is preparing to test fire a long-range missile have drawn renewed scrutiny of US efforts to build a reliable system to intercept such missiles, which is still not fully working.

Washington has built up a complex of interceptor missiles, advanced radar stations and data relays designed to detect and shoot down a North Korean warhead, but tests of the system have had mixed results.

The Pentagon's testing office said in January it may may offer only ''some'' protection, despite about 10 billion dollar a year in development spending under President George W Bush.

In eight intercept tests of the ground-based missile defense system, the interceptor has hit a mock incoming warhead five times.

Testing was suspended after interceptors failed to leave their silos during tests in December 2004 and February 2005 -- failures blamed on quality-control issues.

''When and if the missile-defense system is in an operational status, it has a capability against a limited long-range ballistic missile attack,'' said Rick Lehner, a spokesman for the Pentagon's Missile Defense Agency.

Bush told the military in 2002 to field an initial missile-defense capability by the end of 2004.

It was to be a very limited version of a far more comprehensive space-based missile defense shield -- nicknamed Star Wars -- proposed by the late President Ronald Reagan in the 1980s.

NORTH KOREA MISSILE TESTS The test failures and technical challenges have delayed plans to declare it operational, although commanders say it has a rudimentary capability against a limited missile attack.

The system could be put on alert quickly if US leaders determined there was a sudden threat, defense officials say.

US officials have said North Korea is preparing to test-fire a Taepodong-2 intercontinental ballistic missile with an estimated range of 3,500 to 4,300 kms (2,175 to 2,670 miles) as early as this weekend, based on monitored launch-area activity.

State Department spokesman Sean McCormack warned North Korea on Friday against conducting a ''provocative'' test and said ''we will take necessary preparatory steps to track any potential activities and to protect ourselves.'' US spending on missile defenses soared after Pyongyang surprised US intelligence by firing a multi-stage Taepodong-1 missile over Japan and into the Pacific on August 31, 1998.

The United States has installed nine interceptors in Alaska and two in California. In addition, US Navy cruisers and destroyers with long-range tracking and surveillance capability ply the Sea of Japan.

Boeing Co is the prime contractor for the system's ground-based leg. Lockheed Martin Corp., Northrop Grumman Corp, Raytheon Co and Orbital Sciences Corp. have big related contracts.

Marine Gen James Cartwright, who oversees missile defense as head of the US Strategic Command, said in a published interview last month he was including ship-based interceptors and the Patriot Advanced Capability (PAC-3) anti-missile batteries in the overall system.

REUTERS DH RAI0618