(Corrects March 25 story to clarify comment by Army general on budget priorities in paragraph 12)
WASHINGTON, March 25 (Reuters) - The U.S. Missile Defense Agency on Tuesday said it was optimistic it had found the cause of a failed missile defense test in July 2013 and aimed to carry out a fix for the entire fleet of ground-based interceptors by the end of the year.
Missile Defense Agency Director Vice Admiral James Syring told U.S. lawmakers that officials had accounted for the problem while preparing for the next intercept test in June of the U.S. system that is aimed at defending the United States against a potential ballistic missile attack by North Korea or Iran.
Syring cited rapid increases in missile development by a number of countries and said his highest near-term priority was to conduct another intercept test in June of the ground-based missile defense system managed by Boeing Co. The system includes a "kill vehicle" or warhead built by Raytheon Co and a rocket built by Orbital Sciences Corp.
The Pentagon is also pressing ahead to redesign the Raytheon kill vehicle, which is meant to hit and destroy an enemy missile on contact, start work on a new long-range radar, and improve the reliability of the overall system, Syring told the strategic forces subcommittee of the House Armed Services Committee.
The test planned for June involves an updated version of the Raytheon warhead that is installed on 10 of 30 interceptors in silos in California and Alaska. Additional tests were planned in fiscal 2015 through fiscal 2017, he said.
Syring told the subcommittee that the Pentagon's plans to increase the number of fielded interceptors by 14 to 44 by fiscal 2017 depended on the success of the planned test in June.
He said the ground-based missile defense system was "on solid footing" despite a slight decline in overall fiscal 2015 funding levels. He said he planned to look at increased funding for other aspects of the system in fiscal 2016, on top of plans already announced to spend $1.9 billion over the next five years on the new radar, kill vehicle and software improvements.
The failed intercept last July involved the earlier version of the Raytheon kill vehicle, which failed to separate from the third stage of the booster rocket.
Eventually both versions will be replaced by the new kill vehicle that the agency plans to start funding in fiscal 2015, Syring said.
Army Lieutenant General David Mann, who heads the Army's Space and Missile Defense Command and U.S. Strategic Command's integrated missile defense command, said he was confident in the current system's ability to protect the United States from enemy attacks, given the current rules of engagement.
But he said it was important to continue to upgrade the system and improve its reliability given increasing threats.
Asked if the Pentagon should do more to speed up work on a possible East Coast missile defense site, Mann said it was more important in the current budget environment to invest in increasing the capabilities of the current missile defense system, and improve the reliability of the kill vehicles. "That's where I would put the next dollar," he said.
Current rules call for troops to fire multiple interceptors at each incoming enemy missile, but details of that so-called "shot doctrine" are classified. Better system reliability would allow a reduction in the number of missiles fired, giving the military capacity to respond to a larger number of threats.
Republican members of the subcommittee criticized the Obama administration's moves to cut funding for missile defense in recent years, but Syring said a pause in testing was due to technical problems, not a lack of funding.
He said the agency was also working on several new laser technologies but declined to give any details in the public hearing. (Reporting by Andrea Shalal)