HUNTSVILLE — In response to urgent requests from U.S. military commanders, the Pentagon plans to accelerate the fielding of a missile defense system intended to knock down incoming missiles near the end of their flight, according to the Missile Defense Agency official overseeing the effort.

Commanders have “been screaming” for the Terminal High Altitude Area Defense (THAAD) system, according to U.S. Army Col. Charles Driessnack, THAAD program manager.

“They want it out there soonest,” Driessnack told reporters during an Aug. 16 briefing at the 2006 Space and Missile Defense Conference in Huntsville, Ala.

The THAAD system, which includes interceptor rockets, radar sensors, truck-mounted launchers, and command and control elements, was previously scheduled for deployment in 2012, but is now planned to be available around 2009, Driessnack said.

The plan to get THAAD, which is built by Lockheed Martin Missiles and Fire Control of Orlando, Fla., into the hands of deployed troops ahead of schedule was approved by senior Pentagon leaders earlier this summer, Driessnack said. Accomplishing this goal will require revamping testing plans, he said.

The original testing plans called for testing THAAD in all of the relevant environments that it might operate in around the world, as well as testing its ability to be transported by the various systems needed to bring it to the battlefield, Driessnack said.

Under the new plan, the system will be tested first in various environments and aboard the transportation modes most desired by users. Once that is completed they will be designated available for deployment, Driessnack said. Testing will focus on aircraft, and testing aboard railroad cars has been taken out of the initial testing plans, he said.

Testing conducted to date at White Sands Missile Range, and upcoming demonstrations scheduled for the Pacific Missile Range Facility, will now count towards the requirements for testing in environments such as desert heat and humidity, Driessnack said.

Fielding THAAD sooner through the revised testing plans likely will save the program more than $100 million by shortening the schedule, which requires paying people working on the program for a shorter period of time, Driessnack said.

THAAD scored a successful intercept of a Hera missile in its last flight test, which took place at White Sands Missile Range in New Mexico on July 12. The next test, which is scheduled for the second week in September, will feature a more difficult task with the warhead on the Hera target missile separating from its booster during flight, Driessnack said.

Hitting a separating target is more challenging because sensors will need to discriminate between two objects traveling close together at high altitudes and speeds, Driessnack said. Testers plan to make this task even more difficult by having the warhead separate from the booster very slowly, keeping the two objects even closer together, he said.

Keeping the two objects close together adds challenge to the intercept task by making it difficult to quickly distinguish between the two, Driessnack said.

Shooting down the separating target also is challenging because those firing the THAAD interceptor are aiming only at the warhead, which is about one-tenth the size of a unitary missile, Driessnack said.

The September test will likely be the last intercept test at White Sands, Driessnack said. The next intercept will take place in early 2007 from the Pacific Missile Test Range in Kauai, Hawaii. Driessnack said he is looking forward to beginning testing in the Pacific so that the military can conduct tests without using the corkscrew-like maneuver necessary at White Sands to burn off energy and keep the missile from flying away from the range and into a populated area.

However, the military will keep a THAAD launcher at White Sands, where it will conduct other testing such as a flight test to examine the interceptor’s performance at lower altitudes, which are considered the harshest areas of the flight regime due to high amounts of atmosphere, he said.

Despite the Pentagon’s plan to field THAAD sooner than previously planned, one advocate for the program would like to see it deployed even earlier.

Riki Ellison, president of the Alexandria, Va.-based Missile Defense Advocacy Alliance, said he would like to see the system deployed in both the United States and abroad to protect U.S. allies following the next intercept test due to the threat posed by North Korean missiles.

Ellison said testing should continue on the system in parallel to deploying hardware, but that at least some capability should be brought to the field immediately as a necessary response to the July 4 North Korean missiles tests .