WASHINGTON — A senior Raytheon executive is disputing a congressional watchdog agency’s assertion that a new variant of the company’s sea-based Standard Missile 3 (SM-3) interceptor is being pressed into production prematurely.

In a report released April 20, the U.S. Government Accountability Office (GAO) criticized the U.S. Missile Defense Agency (MDA) for moving programs into production before completion of developmental testing and cited the SM-3 Block 1B interceptor as an example. The report said concurrency between development and manufacturing often leads to costly and time consuming production breaks when design flaws requiring hardware retrofits are discovered.

But Wes Kremer, vice president of air and missile defense systems at Raytheon Missile Systems of Tucson, Ariz., said the SM-3 Block 1B interceptor program has “very little” development and production concurrency. He said what little concurrency there is in the program is necessary to sustain a healthy supplier base, echoing what the GAO said was among the MDA’s justifications for accepting programmatic concurrency.

“The GAO has taken a very … idealistic view of concurrency by saying any concurrency is bad,” Kremer said in a July 3 interview. “And I would argue that if you followed the GAO model, you would shut down your supply base between development and production and you would create a disaster like we have never seen.”

The SM-3 Block 1B is a new-generation variant of the Raytheon-built SM-3 interceptor deployed today aboard U.S. Navy ships equipped with the Aegis Ballistic Missile Defense system. The Block 1B, featuring a two-color infrared seeker that can better distinguish between missile warheads and debris, including decoys, recently had its second straight intercept test after a failure last fall.

According to the GAO report, the MDA in 2009 began procuring Block 1B interceptors in numbers beyond what were needed for testing and with a critical maneuvering technology still immature. According to the report, the MDA’s director said that in addition to testing, these 25 initial interceptors, seven of which could be pressed into operational service, would help prove manufacturing processes while providing data on reliability, sustainability and cost.

Kremer said what little concurrency there is in the Block 1B program is low-risk and that its purpose is to avert production breaks at SM-3 suppliers. Weak demand due to prolonged testing can lead to stalled production lines and component obsolescence, he said. It takes time to restart production lines, he said, adding that a well-run missile defense program will always have some level of concurrency.

The GAO also expressed concern about the MDA’s plan to begin full-rate production of the Block 1B in 2012, before it resolved the issues that caused last September’s failed intercept test and an anomaly that occurred on an SM-3 Block 1A test the previous April. “The flight test failure and the test anomaly occurred in components that are shared between the SM-3 Block 1A and 1B. Program officials are still investigating the reason for these failures,” the report said.

The GAO recommended that the MDA postpone full-rate Block 1B production pending completion of a third straight intercept test. The MDA concurred with this recommendation, the report said.

Kremer said Raytheon would begin purchasing long-lead components for full-rate Block 1B production in 2013 after the three tests have been conducted. More testing will be conducted during the interval between the order of long-lead components and the start of assembly, he said.

Raytheon is continuing to analyze data from the latest successful intercept test but right now it looks like the system performed exceptionally well, Kremer said.

Cristina Chaplain, director of acquisition and sourcing management at the GAO, said via email July 3 that while the Block 1B’s successful test June 26 brings the program closer to full-rate production, more testing is needed.