The next test of the Boeing National Missile Defense (NMD) system is expected to slip until January so that programme officials can fully analyse the string of test failures.

The expected delay is not linked to President Clinton's decision to allow the next US chief executive to determine the future of the trouble-plagued "hit-to-kill" anti-ballistic weapon project. The back-to-back test failures and the lack of a presidential go-ahead effectively delays by at least two years from the 2005 date for fielding NMD.

The last two tests were unsuccessful. The January failure was caused by a cooling problem on the Raytheon exoatmospheric kill vehicle (EKV), while in July a faulty electrical component prevented failed of to release the EKV from the booster. The US Department of Defense (DoD) had planned another launch before year-end.

The $36 billion NMD system would consist of a network of radars; battle management command, control and communications assets, and 100 ground based interceptors (GBI), each carrying a single EKV. A go-ahead from Clinton was required before the DoD could award contracts for constructing a crucial missile-tracking radar site in Alaska.

In leaving the NMD deployment choice to his successor, Clinton called the project "promising" but said "there is not sufficient information about the technical and operational effectiveness of the entire NMD system to move forward with deployment to conclude that it can work reliably under realistic conditions."

He said the booster is untested and there are questions to be resolved about the weapon's ability to deal with countermeasures.

William Cohen, the US defence secretary, promises to "aggressively proceed with the test programme" but says Clinton's action "underscores the importance of having the next president fully involved in decisions."

• In late August, the US Navy successfully tested its SM-2 Block IVA Navy Area Defense weapon. The non-intercept test at the White Sands Missile Range, New Mexico, evaluated the missile's autopilot and aerodynamic performance. The modified Standard SM-2 would be used against short- and medium-range ballistic missiles while the three-stage SM-3 Navy Theatre Wide missile carrying a Light Exoatmospheric Projectile would intercept medium- and long-range missiles.

Source: Flight International