WASHINGTON — U.S. missile defense systems are being pressed into production before they are fully developed and tested, a practice that makes them prone to cost growth, delays and performance issues, according to a new report by the investigative arm of Congress.

The Government Accountability Office (GAO) cited development and production “concurrency” as a major source of problems with the primary U.S. territorial missile shield, now in the latter stages of deployment, and a brewing issue for systems intended to defend Europe. The April 20 report, “Missile Defense: Opportunity Exists to Strengthen Acquisitions by Reducing Concurrency,” appears to confirm longstanding suspicions of missile defense critics who have charged that the Pentagon is rushing untested systems into service.

U.S. Army Lt. Gen. Patrick O’Reilly, the director of the U.S. Missile Defense Agency (MDA), told lawmakers April 25 his agency has reduced a “significant amount” of concurrency in recent years. He insisted, however, that some level of concurrency is necessary to sustain a healthy industrial base and that a failure to do so would increase risk on missile defense programs.

“I think the best balance is to ensure you have very good ground qualification to convince yourself that we have no inherent problems in the designs and then move to flight testing but continue at a low production rate, which most programs do,” O’Reilly said during a hearing of the Senate Armed Services strategic forces subcommittee.

Cristina Chaplain, director of acquisition and sourcing management for the GAO, argued during the hearing that too much concurrency can disrupt the industrial base by causing production stoppages. These can occur when design issues are discovered that require hardware retrofits, she said.

Starting production before the completion of “critical tests” has led to the acquisition of systems that do not perform as intended, the GAO report said. This began with the 2002 presidential direction to rapidly field a system to defend U.S. territory against long-range missile attacks, the report said.

The MDA was given a mandate to field the Ground-Based Midcourse Defense System in 2004, a schedule that required concurrent development, testing and deployment. This led to the premature delivery of upgraded interceptors that required an extensive retrofit that is still ongoing, the report said.

The defense secretary should direct the MDA to prove the newest interceptor design in an operationally realistic intercept test before restarting production. The MDA should take steps to mitigate the impact of delaying the production restart pending a successful intercept test, the report said. The Defense Department concurred with both recommendations.

Similar concurrency issues have occurred with upgrades to the Raytheon-built Standard Missile (SM)-3, the sea-based interceptor that is providing the initial defense of Europe under U.S. President Barack Obama’s so-called Phased Adaptive Approach. Three SM-3 upgrades are in development, and the multiphased approach calls for eventually placing land-based variants on European soil.

The MDA approved production of the SM-3 Block 1B interceptor before completion of developmental testing, according to the GAO. The program’s first intercept attempt failed in September 2011, and there were problems on a nonintercept flight test the previous April, incidents that have caused production and delivery delays.

The report said the defense secretary should direct the MDA to verify Block 1B capability through three developmental flight tests before committing to production of operational hardware. The Defense Department concurred with this recommendation.

The defense secretary should  report to Congress on the root cause of the Block 1B test failure and on future development plans before committing to additional purchases of the interceptor, the report said. Pentagon officials partially concurred; they balked at tying additional SM-3 Block 1B purchases to the report on the cause of the failure.

The report also raised concern about tentative MDA plans to commit to full-scale development of the most capable new variant, the SM-3 Block 2B, more than a year before conducting a preliminary design review. The Block 2B version is expected to cover a broader area than its predecessors and have the ability to shoot down long-range missiles in their boost phase from forward-deployed positions.

The SM-3 Block 2B is the subject of a three-way competition among Boeing Missile Defense of Huntsville, Ala.; Lockheed Martin Space Systems of Sunnyvale, Calif.; and incumbent Raytheon Missile Systems of Tucson, Ariz. Congress slashed the program’s 2012 budget, arguing that too many SM-3 variants were being developed simultaneously, but the MDA is requesting $224 million to get the program going again next year.

The MDA should delay committing to SM-3 2B development until the program clears preliminary design review, the report said. The Pentagon agreed.

The GAO said concurrency issues affect numerous other MDA programs and recommended that the Pentagon’s acquisition czar review all agency procurement programs  for concurrency. The acquisition czar also should review the Phased Adaptive Approach for potential concurrency issues and adjust the program’s schedule accordingly, the report said.

The Pentagon concurred with both recommendations.