Over the past 70 years, the United States has invested in $350 billion in ballistic missile defense, but these defense systems, intended to defend against long-range, nuclear-armed missiles, may not be capable against realistic missile threats, according to a report commissioned by the American Physical Society.

The report, co-chaired by University of Michigan physicist James Wells and prepared by APS's Panel on Public Affairs, suggests that the U.S.'s defenses against nuclear-armed intercontinental ballistic missiles, or ICBMs, are currently low and will likely continue to be low for the next 15 years.

Titled “Ballistic Missile Defense: Threats and Challenges,” the report notes that despite decades of effort, no missile defense system thus far developed has been shown to be effective against realistic ICBM threats. ICBMs are ballistic missiles with a range of more than 3,500 nautical miles.

"Right now, the system is not completely effective, and by that I mean if a potential adversary like North Korea were to launch ICBMs toward the United States, we could not guarantee that millions of people wouldn't die," said Wells. "That's the level of reliability one would hope a system would have, and we do not see a clear path to reach that level of reliability over the next 15 years."

The researchers will present the report during a webinar, "Ballistic Missile Defense: Threats and Challenges," from noon-1:30 E.T., Wednesday, Feb. 16. Register to attend. 

Wells became involved with APS's Panel on Public Affairs at the encouragement of Homer Neal, a renowned U-M physicist and former president of the APS, who felt that U-M researchers should be involved in the public sphere.

The report drew together 13 physicists and engineers, including Alec Gallimore, dean of Michigan Engineering, to examine whether current and proposed systems intended to defend the United States against nuclear-armed North Korean ICBMs are—or could be made—effective in preventing a successful ICBM attack by North Korea on the United States.

"With the Biden administration’s review of missile defense expected later this year, it is critical to have a careful technical assessment of its capabilities that our leaders can use to more clearly evaluate the economic and security costs of pursuing missile defense systems, as well as a careful assessment of their possible benefits, " said Frederick K. Lamb, chair of the study, physics professor at the University of Illinois at Urbana-Champaign, and a missile defense expert. "Having looked at the issue in detail, we have come to the conclusion that the current U.S. missile defense system is unreliable and ineffective against even the small number of relatively unsophisticated nuclear-armed ICBMs that we considered, and that creating a reliable and effective defense remains a daunting challenge."

In preparing the report, the committee reviewed extensive government information and reports produced by various agencies, including the Government Accountability Office and the Office of the Director of Operational Test and Evaluation, and the National Academy of Sciences. The committee also studied reports by non-governmental experts and institutions.

The study aims to provide a realistic view of current U.S. capabilities and an understanding of the prospects for being able to defend against the ICBMs North Korea might deploy within the next 15 years. The report concludes that the unreliability and vulnerability to countermeasures of the sole existing system intended to counter North Korean ICBMs—the Ground-based Midcourse Defense—means that it has limited effectiveness. Because of the difficulty of correcting these deficiencies in a timely or cost-effective way, this system cannot be expected to provide a robust or reliable defense against more than the simplest attacks by a small number of relatively unsophisticated missiles within the 15-year time horizon of this report.

Furthermore, the report finds that other systems that have been proposed, which would attempt to intercept ICBMs during their first few minutes of flight while their rocket engines are firing—called the boost phase—would face very difficult technical challenges. The report concludes that systems of this type based on land, ships, or aircraft would be unable to defend all of the continental United States. At best, a particular system could theoretically defend part of the U.S.

Boost-phase systems based in space would require many hundreds of weapons orbiting on space platforms to theoretically defend against a single North Korean ICBM, and thousands to defend against five ICBMs launched within a short time. This type of system would be very expensive and vulnerable to being disabled by anti-satellite weapons.

"Despite decades of work and costs totaling more than $350 billion, the United States still has not been able to field a defense that would be able to intercept even a small number of relatively unsophisticated ICBMs reliably and effectively," said Lamb. "But even the pursuit of such a defense has wider implications, including giving Russia and China reasons to expand their nuclear arsenals. The costs and benefits of this effort need to be weighed carefully."

More Information:
Professor James Wells

Expert U-M Physicist James Wells was recently featured in a recent CNN news report regarding U.S. ballistic missile defense systems capabilities. You may watch the news clip here.