Army cutbacks prompt questions about vulnerabilities to air threats.

A sizeable reduction planned for the Army's air-and-missile-defense force is touted by proponents as a necessary move that reflects the realities of current conflicts. But critics worry that the cutbacks will leave ground combat units more vulnerable to aerial attacks, and increasingly dependent on Air Force and Navy weapons to protect them from enemy missiles.

Under the reorganization, the Army will convert its 10 active-duty divisions into 48 independent brigades. The current air-defense force, composed of 10 battalions of about 500 soldiers each, will be downsized to four battalions. These four units will be melded with the Army's 10 Patriot air-missile defense battalions. The members of the remaining six battalions will be reassigned to other Army occupations now in higher demand, such as military police and infantry.

With the expectation that the Air Force and Navy will be in control of the air space in future wars, the Army decided that 10 air-defense battalions was a luxury it could not afford.

"Looking at what the Air Force can deliver, we decided to take some risk and we took it," said Gen. Kevin Byrnes, who heads the U.S. Army Training and Doctrine Command.

But experts warn that, even though the Air Force has proved it can achieve "air superiority," it is not clear what that term means exactly, noted a retired air-defense officer who did not want to be quoted by name. "When they say 'air superiority,' where is that? In what regime? What targets are included?" he asked.

The Air Force typically has focused on eliminating the threats from surface-to-air missiles, but the Army expects that most threats will come from unmanned aircraft and cruise missiles. "In my opinion, there is a capability gap that an enemy can exploit," the retired officer said. For that reason, he opposes the Army's decision to eliminate air-defense battalions. "The air defense community has fewer and fewer units to take out UAVs and cruise missiles."

Maj. Gen. Michael A. Vane, commander of the Army Artillery School, downplayed the significance of the cutbacks, describing them as part of the "transformation" under way in the Army. "Every one of us is a product of our background," he said. "That makes us good at what we do, but it also holds us back."

As expected, traditional thinkers in the Army will find it hard to accept that the Air Force and the Navy can offer the same or better protection than ground-based air defense. "Some of us are used to doing it from the ground. That's how we've always done it," said Vane.

He explained that the restructuring leaves the Army with a smaller air-defense force but with more relevant capabilities. By combining the four air-defense battalions with 10 Patriot battalions, the Army will create 14 "composite" units with additional capabilities they didn't have before, Vane said. Each will be made up of four elements, designed to defeat four threats: ballistic missiles, cruise missiles, unmanned aircraft and RAM, an acronym used to designate rockets, artillery and mortars.

Vane cautioned that these decisions are not final yet. "That future number is soft and still evolving with ongoing analysis," he told National Defense.

The reduction of short-range air defense units--which are equipped with Stinger missile launchers--is calculated on the premise that the Stinger will not be able to defeat advanced cruise missiles, because it has a range of only 3 kilometers.

"The enemy overmatches the capability of Stinger," Vane said at a recent news conference.

While the Patriot will be the primary antiaircraft and anti-missile weapon, the Stinger will offer "some limited capability" against cruise missiles, he said. The Army also is developing a surface-to-air missile launcher, called Slamraam, which will shoot the same missiles that Air Force and Navy pilots fire from fighter jets.

The Army, however, remains most vulnerable against rockets, artillery and mortars. Until more advanced technologies can be developed, the "counter-RAM" piece of the composite battalion most likely will be delayed. "We didn't think there was a technological solution," Vane said.

That is bad news for the Army, because rockets, artillery and mortar strikes are--after improvised explosive devices--the second-biggest killer of U.S. troops in Iraq.

The most desirable technology to defeat RAM is laser weapons, said Vane. Although the Army already owns a laser that can shoot down rockets, it is too large to be deployable. A smaller system won't be available until 2012, said Vane.

Kinetic weapons often are not useful against RAM threats in urban fighting, because they put civilians at risk, he noted. The Army's air and missile defense battle lab is working on classified programs in this area, but it is unlikely that any silver bullet will emerge in the near term.

The current thinking is that the best way to defeat rockets, artillery and mortars is to take a "holistic" approach, said Col. Paul McGuire, commander of the air and missile defense battle lab. That means it's not enough to just try to defeat an incoming round. "We are looking at ways to sense the battlefield, deny those launches before they happen," McGuire said. "If they do happen, we warn the force, to make sure people can get in protective cover."

This "mix of capabilities" is the only way to address the RAM problem today, he said.

Vane admitted he was somewhat disappointed that directed-energy weapons have not materialized as quickly as expected. "Kinetic energy still is part of the solution," he said. "We've been watching directed energy for a number of years. It has looked very lucrative to us in terms of efficiency and logistics, but so Ear, technology hasn't gotten us there."

Unlike high-energy kinetic weapons, lasers would "soft kill" targets without much debris fallout. The beam would burn a hole in the rocket or artillery round.

Chemical lasers, such as the Army THEL (tactical high-energy laser) are powerful weapons, but they are too large and heavy, said Vane. The next generation of directed energy systems, the solid-state lasers, will be much lighter and mobile, but the technology still is years away.

"Kinetic energy and directed energy will be complementary capabilities for many years to come," Vane said.

The contractor for the THEL weapon, Northrop Grumman Corp., has received Army funds to study options for mobile laser weapons. The company proposed repackaging the THEL system so it would fit into three standard shipping containers. This work would take 18 to 24 months, said Art Stephenson, vice president for directed energy systems at Northrop Grumman.

The company also is studying the use of guided rockets to counter mortars. Solid-state lasers, said Stephenson, are about six to nine years from becoming mature enough to compete with chemical lasers.