“A good offense is the best defense” is a well-known phrase used by Gillian Bussey, the Pentagon’s director of the Joint Hypersonics Transition Office, to explain the difficulty of stopping attacking hypersonic weapons traveling at five times the speed of sound. 

As Bussey sees it, the capability to deliver a lethal hypersonic counterattack, which could be described in terms of a “deterrence posture,” might deter enemies from considering an attack with hypersonic weapons.

According to a statement from the Defense Department, Bussey noted that the cost of engineering offensive vs. defensive weapons is guiding U.S. strategy. “Defending against hypersonics is an expensive and complicated endeavor, while it remains less expensive to develop and launch a hypersonic offense. That’s why, even though the department is focused on both offensive and defensive capabilities, it’s prioritizing offensive systems,” Bussey said. “Research into both defensive and offensive systems yields valuable knowledge that can be used for both.”

However, Bussey did reference the possibility that hypersonic projectiles could operate with a dual-use functionality, meaning key elements of the weapon such as its kill vehicle could be used for both offensive and defensive purposes. Perhaps hypersonic weapons themselves could even be used as interceptors. 

“What has the maneuverability, altitude, reach and speed to hit a hypersonic missile? A hypersonic missile,” Bussey said. “While technology for defensive and offensive systems are different, including seekers, guidance and booster technology, the fundamental design of an offensive or defensive kill interceptor vehicle can be the same.

“We’ve seen a number of proposals using what could be an offensive strike weapon used as an interceptor and vice versa,” she said. 

Bussey’s approach to hypersonics is entirely aligned with the Missile Defense Agency’s emphasis on integrating offensive and defensive capabilities given the high number of potential warfighting synergies. 

Kris Osborn is the Defense Editor for the National Interest. Osborn previously served at the Pentagon as a Highly Qualified Expert with the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Master’s Degree in Comparative Literature from Columbia University.

Image: Reuters.