Defense Secretary Jim Mattis said last week that additional spending on missile defense against the North Korean threat awaits a strategy review.
"It's a prioritization," Mattis said. "Right now, I think we can first do the study to make sure what is the requirement, what are we lacking."
The goal is to "define the problem well enough that we are targeted like a laser beam on exactly what we need," he said in testimony June 12 to the House Armed Services Committee.
Mattis was responding to questions from Rep. Doug Lamborn, R-Colo., who said, "I know President Trump wants to have a state-of-the-art missile defense. I'm just concerned we're cutting the budget for missile defense research and development. Why are we not putting our money where our mouth is?"
The SecDef replied, "I want to get this right before we come to you and spend a lot of money. "You're going to count on us that we did our homework, and we've not yet done it."
He stressed that he was not disagreeing that the U.S. must spend more on missile defense.
The Trump administration has proposed an overall $7.9 billion budget for the Missile Defense Agency in fiscal 2018, a relatively modest increase that essentially flat-lines the hit-to-kill anti-missile program.
In his June 7 testimony to the HASC strategic forces subcommittee, Vice Adm. J.D. Syring, head of the Missile Defense Agency, said the proposed $7.9 billion would meet current and future needs for the "development, testing, deployment, and integration of interceptors, sensors, and the command, control, battle management and communications (C2BMC) system for the Ballistic Missile Defense System."
At the hearing, and at an earlier Pentagon briefing, Syring said the May 30 "direct collision" of a Ground-based Midcourse Defense (GMD) interceptor missile launched from Vandenberg Air Force Base in California against an Intercontinental Ballistic Missile-class target launched from the Reagan Test Site on Kwajalein Atoll in the Marshall Islands showed the U.S. can defend against the North Korean threat at least through 2020.
"The intercept of a complex, threat-representative ICBM target is an incredible accomplishment for the GMD system and a critical milestone for this program," Syring said. "This system is vitally important to the defense of our homeland, and this test demonstrates that we have a capable, credible deterrent against a very real threat."
The interceptor system currently consists of 36 ground-based interceptors at Fort Greely, Alaska, and Vandenberg. The Missile Defense Agency is expected to finish fielding all 44 interceptors by the end of 2017.
At an earlier Pentagon briefing May 23, Gary Pennett, the Missile Defense Agency's director for agency operations, said the review of missile defense ordered by Mattis will be completed by the end of this year but will not "preclude moving forward" with improvements for the system.
Pennett said the agency plans to move ahead with a $5 million study to look at the possibility of establishing an Atlantic radar. The study will assess "the feasibility of appropriate tracking and discrimination sensor capabilities to support the defense of the United States against emerging, long-range, ballistic missile threats from Iran," he said.
One potential drawback is the enormous cost of testing the system. Syring noted that the May 30 successful intercept of the ICBM-type target cost $244 million.