Directed Energy And The Future Of Missile Defense

Richard M. Harrison

Originally published at

In the March 23, 1983, address that formally unveiled the Strategic Defense Initiative (SDI), President Ronald Reagan famously outlined a vision that challenged the “balance of terror” that governed relations between the U.S. and USSR. Reagan proposed an alternative to continuing to live with the imminent threat of thermonuclear war: the development and deployment of defensive capabilities able to eliminate nuclear-tipped ballistic missiles.

However, aside from a few dozen battle-untested ground-based interceptors in Alaska and California that may be capable of intercepting an intercontinental ballistic missile, perhaps the closest the United States has come to truly realizing Reagan’s vision of being able to shoot down nuclear-armed missiles was in the Defense Department’s efforts in recent years to strap a laser to a Boeing 747 airliner. This can hardly be the robust national missile defense architecture that President Reagan had in mind. Yet Reagan’s SDI speech, and the subsequent National Security Decision Directive 85 laid the foundation for the Pentagon to aggressively pursue new technologies, including the use of directed energy systems for protection against ballistic missile attack.

False starts…
The road has not been easy, as the history of the Airborne Ballistic Laser (ABL) program, the highest-profile and best-funded directed energy system program to date, amply demonstrates. Originally conceived in the 1970s, the ABL was fast-tracked by the Pentagon during the George W. Bush administration as part of America’s “system of systems” of post-ABM treaty protections against ballistic missile attack. But after more than a decade of cost overruns and technical difficulties, the ABL was ultimately cut back by a weary Pentagon and reconstituted as strictly a “demonstration program” of limited scope and application.

The reasons were myriad. The ABL’s chemical laser turned out to be extremely heavy, it used highly toxic chemicals that complicated logistics for refueling, and the weapon was limited by the chemical supply on board the aircraft. Additionally, it was both costly and strategically infeasible to operate the large, cumbersome aircraft in various battlespaces for long durations of time.

The failure of the ABL notwithstanding, there are compelling reasons why the future of U.S. missile defense is inextricably linked to the use and exploitation of directed energy systems.

…but much promise
For one thing, directed energy weapon (DEW) systems are not new. Several are already employed on the battlefield or in various stages of development in defense labs. Although laser weapons are more prevalent, high-power microwaves (HPM) and charged particle beams (CPB) are also types of directed energy weapons.

It is increasingly clear that DEW is a technology whose time has come. The Department of Defense invested heavily in both CPB and HPM research during the 1970s, but ultimately scrapped development as a result of economic and technological constraints. Not so now. Recent developments by Boeing’s impressive counter-electronics high power microwave advanced missile project (CHAMP) demonstrated that HPM weapons can be used to generate an electromagnetic pulse, which destroys the electronics of a target location, facility or vehicle. This technology can be adapted for missile defense by using it to disable an adversary’s missile guidance system network, effectively removing an enemy’s ability to successfully guide missiles to designated targets.

However, it is lasers that represent a true ray of hope for new missile defense systems. Lasers are able to concentrate energy on a target and have the proven ability to cause physical destruction. Laser weapons also possess several inherent advantages over kinetic weapon systems. First, lasers operate at the speed of light, so they reach their target immediately, with pinpoint accuracy across large distances.

Although laser weapon systems will require significant upfront investment, they offer far reduced cost per shot over traditional interceptor missiles. According to experts, excluding development costs, firing an interceptor missile costs over a million dollars, but the equivalent shot from a laser weapon would only cost tens of dollars.

Laser weapons can engage in multiple targets with an endless magazine of ammunition—limited only by the amount of power available to fuel the weapon system. Most important, lasers avoid the technical difficulty of trying to “hit a bullet with a bullet,” as required when a missile interceptor is used to kinetically destroy a missile.

The road ahead
Of course, not all lasers are created equal. Currently lasers serve several purposes in warfare, including but not limited to guiding munitions, range finding, targeting, and blinding optical sensors. But these lasers are relatively weak compared to those with the beam strength required to shoot down a missile. A laser’s power level, measured in watts, is a key differentiator used to assess its capability to destroy targets of various size and speeds. Lasers operating with power levels of over 100 kilowatts are able to shoot down UAVs, rockets, artillery, and mortars; and powerful megawatt-class lasers are capable of destroying anti-ship cruise missiles and ballistic missiles.

Today, chemical lasers, like the one found on the mostly defunct ABL program, are the only megawatt-class lasers capable of destroying an intercontinental ballistic missile. And they are likely the only type of laser to reach the megawatt power level in the immediate future. But with advancements in technology and adequate funding, non-chemical lasers (such as free electron lasers) are positioned to play a role in combating short-range and anti-ship cruise missiles in the near term—and long-range ballistic missiles in the longer term.

Lasers are not without their limitations, however. Lasers shoot in straight lines, so they are not effective for targeting missiles over the horizon—though this may be mitigated by redirecting laser beams off mirrors affixed to UAVs, blimps, or satellites. As well, due to the concept of “thermal blooming,” lasers struggle to destroy targets heading directly at the laser beam, although this problem does not occur with a ballistic missile due to its trajectory. The biggest obstacle to the vitality of laser weapon systems is undoubtedly the U.S. government itself. Due to inadequate past performance and the current state of economic malaise, directed energy weapons systems will likely continue to struggle for funding.

That represents a critical error. If the U.S. wishes to remain an unparalleled military force capable of defending its homeland and allies abroad from an expanding array of missile threats, then it is imperative to innovate. DEWs are not a panacea for missile threats; however, they do offer very real and significant benefits over traditional systems. Lasers are not meant to replace kinetic weapon systems, but rather act in combination with them to provide the missile defense architecture that President Reagan envisioned—the one that America today so urgently needs.

Richard M. Harrison is Research Fellow and Program Officer at the American Foreign Policy Council in Washington, D.C., where he directs the Council’s work on defense technology.

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