Conventional Prompt Global Strike: Progress, Prospects, and Implications for Strategic Stability

For over a decade, the United States has sought to develop long-range, hypersonic conventional weapons for the Conventional Prompt Global Strike (CPGS) program. Successfully testing the Advanced Hypersonic Weapon in November 2011 marked an important breakthrough, although a second test in August 2014 was unsuccessful. Developing these weapons could have important implications—both positive and negative—for Asian-Pacific regional security.

Based on his recent research, James Acton analyzed the status of the CPGS program and assessed its implications for regional and global security. Tong Zhao moderated the event. Paul Haenle introduced James Acton and made opening remarks.

Discussion Highlights

• Current Status of the CPGS Program: After two failed tests in 2010 and 2011, development on the Hypersonic Technology Vehicle-2, a glider system intended for boost-glide missiles, effectively stalled. Panelists explained that the CPGS program shifted to developing Advanced Hypersonic Weapons. These long-range conventional missiles remain under development and will potentially include both land- and sea-based varieties with a range of up to 8,000 kilometers.
   
• Capabilities-Based Approach and CPGS Applicability: Panelists described how the Defense Department takes a capabilities-based approach to developing weapons technologies. It therefore remains open to debate whether, when, and how CPGS weapons might be deployed in the future. One panelist referred to a 2007 statement by former deputy assistant secretary of defense Brian Green, who suggested that development criteria should focus on the attributes of potential targets rather than specific military scenarios. Panelists speculated that CPGS weapons may be suitable for targeting highly defended, high-value assets, such as missile installations or terrorist targets, because these missiles could be deployed quickly and accurately to minimize collateral damage. 
   
• Limited Precedent For Practical Use: Despite theoretical promise, there is little documented evidence from past military operations to suggest that CPGS weapons could accurately target mobile targets like enemy missiles, panelists pointed out. Accuracy depends on nearly continuous radar tracking coverage and reliable discrimination between nuclear weapons, conventional weapons, and non-targeted military and civilian assets. In 2006, Israel successfully destroyed 80 percent of targeted Hezbollah rocket launchers, but the operation had the advantage of being preemptive. CPGS weapons usage may not have this element of surprise, and even if it did, an 80 percent success rate would leave too great a margin for error if targets include conventional or nuclear missiles.
   
• Balancing Risks and Benefits: The issue of warhead ambiguity links closely to the debate surrounding CPGS development, Acton said. The danger that a conventional CPGS missile could be mistaken by another country for a nuclear one creates a risk of miscalculation and an inadvertent nuclear strike in response. There are other dangerous ambiguities, such as the fact that observing countries may be unable to determine from a missile’s trajectory if they or a neighboring country is the intended target. The United States must weigh the enhanced deterrence and advanced capabilities that CPGS weapons provide against high development costs and risks of miscalculation and threat escalation, Acton said. This analysis remains one of trade-offs, as no CPGS weapons system possesses all the attributes needed to distinguish its payloads from nuclear ones. These characteristics include missile deployment areas, deployment systems, and missile trajectories.
   
• Time to Talk Is Now: Panelists maintained that confidence-building measures between the United States and other actors are necessary to ameliorate concerns of ambiguity and escalation. Addressing warhead ambiguity requires that states collaboratively develop clear procedures for inspections, surveillance, and notifications. Data exchanges, declarations, and joint research studies could help to reduce escalation concerns. The United States and China should work together now while CPGS weapons remain in development, panelists concluded.

James Acton

James Acton is a senior associate and co-director of the Nuclear Policy Program at the Carnegie Endowment for International Peace. His research spans the field of nuclear policy. His most recent work focuses on Conventional Prompt Global Strike weapons and is widely regarded as among the most influential and authoritative research ever conducted on this subject. 

Paul Haenle

Paul Haenle is the director of the Carnegie–Tsinghua Center based at Tsinghua University in Beijing, China. In addition to running the Carnegie–Tsinghua Center, Haenle is also an adjunct professor at Tsinghua, where he teaches undergraduate and graduate-level courses to Chinese and international students on international relations and global governance.

Tong Zhao

Tong Zhao is an associate in Carnegie’s Nuclear Policy Program based at the Carnegie–Tsinghua Center for Global Policy. His research focuses on strategic security issues, including nuclear arms control, nonproliferation, missile defense, strategic stability, and China’s security and foreign policy.