WASHINGTON — The best way to defend the United States from a cruise missile attack may be to focus on where adversaries are keeping the ships and aircraft that could fire such a weapon and not take a broader approach to counter any possibility, the vice chairman of the U.S. Joint Chiefs of Staff said Feb. 23.

The U.S. has yet to reach a conclusion in the long-term debate on how to defend the U.S. homeland from cruise missiles, but Gen. John Hyten, the Pentagon’s no. 2 officer, said the focus needs to not be entirely on defeating cruise missiles in the terminal phase, which is the tail end of a missile’s trajectory to a target.

“If you look at the cruise missile problem from the terminal phase, that basically means you have to build giant point defense radars or some kind of aerial defense radar because even a Low-Earth Orbit satellite has a difficult time seeing most cruise missiles,” Hyten said during a Center for Strategic and International Studies event focused on missile defense. “You have the ability to see some and we should make sure we explore that and understand that piece, but to deal with the cruise missile threat, the first sensor, first critical sensor piece of the puzzle is the platform sensor because the cruise missile is launched from that platform.”

With the exception of a possible nuclear-powered cruise missile, the weapon has to be launched from a platform that needs to come relatively close to the target, Hyten explained. This could be a platform such as a submarine, ship or aircraft.

“The key piece of that is to have a clear understanding of where the platforms are that could threaten the United States with cruise missiles,” he said. “You understand where the platforms are, again, you effectively respond and effectively deter and message your adversary when you see a platform approach an area that is threatening the United States.”

This approach is commonly referred to as “left of launch,” meaning the focus is to take out a missile’s launcher before it has a chance to be shot rather than shooting the missile on its journey to a target.

The next step, Hyten said, would be to figure out how to defend critical infrastructure from such attacks. This means determining what critical elements need defending and then deciding on a point defense architecture “because you can’t put a point defense architecture around everything in the United States. It’s impossible.”

A Congressional Budget Office report released earlier this month, which looked at the threat of cruise missiles to the U.S. homeland and examined possible architectures for a nationwide defense, determined that the threat could be defeated using available technology, but it would be expensive if the strategy was to employ a wide-area defense.

CBO determined that buying systems that the military uses — a mix of airborne or space-based radars, surface-to-air missiles and fighter aircraft —would cost around $75 billion to $180 billion to purchase and operate over a 20-year period. The report noted that fielding “additional regional or local defenses to protect Alaska, Hawaii, and U.S. territories would add to the cost.”

Additionally, the report noted it would be complicated to run defense systems in the homeland due to heavy civilian aircraft traffic as it would take longer to positively identify and engage threats.

The window to respond is already relatively limited due to the shorter range of cruise missiles when compared to ballistic missiles and there is an increased challenge to detect and identify, through a variety of clutter, stealthy cruise missiles, which are by nature more difficult for radar to spot.

The report also notes that while cruise missile capabilities exist, adversaries have many “attractive” alternatives to using them, such as less expensive or more damaging options. “Decision makers would need to consider whether the cost of a wide-area cruise missile defense was proportionate to the overall risk posed by [Land-Attack Cruise Missiles],” the report read.

CBO considered four primary architectures to defend the United States against cruise missiles including using radar on High-Altitude, Long-Endurance Unmanned Air Vehicles (HALE-UAVs), modified commercial aircraft and aerostats as well as spaced-based sensors.

HALE-UAVs would likely cost $77 to $98 billion over 20 years while space-based radar would cost roughly $106 to $179 billion. On the increasingly expensive side, modified commercial aircraft would cost an estimated $187 to $246 billion. Aerostats could potentially be the most expensive — and was something the U.S. Army pursued recently until the program was killed in 2017 — at $98 to $466 billion.

The Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System — or JLENS for short — was canceled after one of the tethered aerostats escaped its mooring at Aberdeen Proving Ground, Maryland, and lumbered through the skies across Maryland and Pennsylvania until settling down in a wooded glen where Pennsylvania state troopers were ordered to open fire on the system to get it to deflate.

The Army had procured just two systems from Raytheon before cutting the program short and ending one of the few cruise missile defense programs in the works.

The service has procured two Iron Dome systems from Israeli defense company Rafael that will be used as deployable cruise missile defense systems on an interim basis. It is also developing an enduring cruise missile defense capability for point defense as part of a larger program focused on defense against drones and rockets, artillery and mortars as well as cruise missiles.

Jen Judson is an award-winning journalist covering land warfare for Defense News. She has also worked for Politico and Inside Defense. She holds a Master of Science degree in journalism from Boston University and a Bachelor of Arts degree from Kenyon College.

More In Pentagon