Attacking intercontinental ballistic missiles (ICBMs) spend roughly twenty minutes traveling through the “midcourse” phase in space which presents a time window that cutting-edge missile defense systems, such as the Ground-Based Interceptor (GBI), can launch their interceptors. 

Unless a missile is destroyed just after launch, the optimal window to destroy an enemy ICBM is during the midcourse phase when the weapon travels through space. Once an ICBM re-enters the earth’s atmosphere during the terminal phase of flight, it can be very difficult to intercept given its descent speed. 

ICBM interceptor defenses have been largely land-based but a new Raytheon-built variant of the Standard Missile 3 (SM-3) is increasingly capable of destroying ballistic missiles and, even ICBMs, during the midcourse phase of flight.  It’s called the SM-3 Block IIA, and the U.S. Missile Defense Agency just announced a major $867 million deal with Raytheon to produce and deliver the weapon. Unlike standard GBIs which fire from land, the SM-3 IIA can launch from ships at sea using the U.S. Navy’s Aegis Combat System. 

The SM-3 Block IIA, which has been in existence for several years, incorporates a software upgrade enabling the integration of more precise and discriminating sensor technology, longer flight times, and greater range beyond the earth’s atmosphere.

The SM-3 is a kinetic energy warhead able to travel more than 600 miles per hour that carries no explosive warhead but instead relies on the force of impact to destroy targets. ICBM defense would be a game-changer for missile defenses, given that SM-3s fire from both U.S. Navy ships and land-based Aegis Ashore launchers in Poland and Romania. Land-based applications of the SM-3 in Europe have been deployed to defend against long-range ballistic missile threats on the continent. Now, ship-fired SM-3s could bring new intercept possibilities over ocean areas potentially less reachable by existing defenses.

The SM-3 IIA, which has already demonstrated an ability to intercept short and medium-range ballistic missiles, is the latest high-tech SM-3 variant. Compared to previous SM-3 variants, the SM-3 IIA is larger, more accurate, and has a longer range. SM-3 missiles, launched from both U.S. Navy ship Vertical Launch Tubes and land-based Aegis Ashore systems can travel beyond the roughly sixty-mile limit of the earth’s atmosphere.

However, until now, SM-3 IIAs have not generally been thought of as a weapon capable of intercepting larger, faster, space-traveling ICBMs.

Not only do ICBMs operate at much higher altitudes than short or medium-range ballistic missiles, but they are much faster.

Traveling as fast as 10,000 miles per hour in some cases, ICBMs are a much

harder target to hit, particularly if decoys and other countermeasures are deployed. However, the SM-3 IIA’s size, range, speed, and sensor technology could enable it to collide with enemy ICBMs at the beginning or end of its flight through space, where they are closer to the boundary of the earth’s atmosphere.

As Pentagon developers describe it, an SM-3 Block IIA missile is a larger version of the SM-3 IB in terms of boosters and the kinetic warhead, allowing for longer flight times and engagements of threats higher in the exo-atmosphere.

The U.S. Missile Defense Agencies’ 2016 budget item justification further specifies SM-3 IIA technological advancements, which include more than “doubled seeker capacity” and “more than tripled divert capability.” The budget documents add that the new SM-3 IIA technologies include a “lightweight nose cone, advanced kinetic warhead” and twenty-one-inch second and third stage rocket motors. Aerojet Rocketdyne’s MK 72 booster and MK 104 dual-thrust rocket motor provide the first and second-stage propulsion.

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: Flickr/U.S. Department of Defense.