WASHINGTON -- While the Pentagon continues to pursue directed-energy weaponry, the building's top weapons buyer wants to temper expectations.

Frank Kendall told reporters this week that 30 years of work on laser arms have led him to conclude such systems are not the "panacea" they sometimes are made out to be.

"They could be useful if they get to a level of both power, [transmission], and size, weight and power that are manageable," he said, "but we're not at the point where we can decide we're going to put lasers in the force."

Kendall's vision of directed energy is a more sober one than others in the Pentagon and in industry previously have offered. A longtime dream of the Defense Department, the technology has been described as almost-there for quite some time. In March, engineers at Lockheed Martin said they believe laser weapons are ready for use now, and practically every branch of the department is now publicly touting their investments in directed-energy capabilities.

In the next five years, the Air Force plans to fire lasers off a fighter jet; the Navy already has a directed-energy weapon onboard the afloat forward-staging base Ponce, which saw deployment to the Gulf last year; and the Missile Defense Agency is investigating the technologies. The Army also has invested in researching the technology.

Kendall was clear he believes directed energy could be a benefit to the Pentagon going forward, and that the department is dedicated to spending prototyping dollars over the next three years to see if the technology can continue to mature.

"We have a number of prototype programs in directed energy, different technologies going, and they culminate in the next three years, roughly," he told reporters Sept. 7 after the annual Common Defense conference in Washington. "At that point we’ll be able to make a decision on what to take forward in the directed-energy world."

But, he warned, there are serious limitations that could make it unlikely that a directed-energy weapon is ever truly effective enough to be used in combat. Those limitations go beyond the long-standing question of how much power such a system would require to be effective, and the hurdles of employing it outside controlled laboratory conditions.

"There are limitations with lasers because of weather. There are limitations of lasers because of behavior, beams of light in the atmosphere, and the possibility that [an enemy] could harden against them," Kendall explained. "They are not a panacea."

However, one area in which Kendall said a laser weapon could be "very helpful, potentially," is countering small, commercial unmanned aerial systems.

"They’re being used by ISIL, they’re being used by Russia in Ukraine for targeting and sometimes for delivering lethal mechanisms. That is the type of target that is relatively soft to a laser, and it’s also short-range in most cases, so you don’t require as much power," Kendall explained.

Aaron Mehta was deputy editor and senior Pentagon correspondent for Defense News, covering policy, strategy and acquisition at the highest levels of the Defense Department and its international partners.

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