Prompt Global Strike (PGS) is a United States military effort to develop a system that can deliver a precision conventional weapon strike anywhere in the world within one hour,[1][2] in a similar manner to a nuclear ICBM. Potential scenarios that would require such a fast response might include an impending North Korean missile launch.[3] In April 2010, Marine Corps General James Cartwright explained the system's rationale, stating that "Today, unless you want to go nuclear, [the conventional military response time is] measured in days, maybe weeks".[4]
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The PGS system will be designed to complement existing American rapid-response forces, such as Forward Deployed Forces, Air Expeditionary Groups (which can deploy within 48 hours) and carrier battle groups (which can respond within 96 hours).[3] Possible delivery systems include:
In 2010, the United States Air Force prototyped a PGS system based on a modified Minuteman III ICBM.[4] In March 2011, Air Force Major General David Scott stated that the service had no plans to use a sea- or land-based ICBM system for Prompt Global Strike, as they would be expensive to develop and potentially "dangerous." Instead, efforts would focus on a hypersonic glider.[5] However, the following day, Air Force Chief of Staff Norton Schwartz said that an ICBM-based PGS system was still an option.[6]
The warhead is expected to be a maneuverable vehicle, weighing around 2 tonnes (4,400 lb) including its payload, and will be able to deliver a unitary penetrator, numerous smart munitions, or even independent UAVs.
The administration of George W. Bush considered developing such a weapon in the 2000s, but rejected the idea because of fears that an ICBM-launched weapon would trigger the Russian nuclear-launch warning system, potentially provoking a nuclear war.[7] However, the Obama administration continued development of the system later in the decade, believing that it could allow the U.S. to shrink its nuclear arsenal while maintaining its deterrent and quick-strike capabilities.
A potential enemy cannot be certain that a launched ICBM contains only a conventional warhead, not a nuclear one. It is thus currently unclear what design features or precautions could convince China and Russia, two countries with launch-detection systems and nuclear ICBMs, to ignore their early-warning systems. Current ideas include a low-trajectory missile design, or allowing Russian and Chinese inspection of PGS missile sites.[4][3]
On 11 April 2010, United States Secretary of Defense Robert Gates indicated that the United States already possessed a Prompt Global Strike capability.[8] This coincided with the New START disarmament treaty signed on 8 April 2010, which set new, lower limits on ballistic missiles and their warheads. The treaty does not distinguish between conventional and nuclear versions of weapons, meaning any ballistic PGS missiles and warheads would count toward the new limit. However, the U.S. State Department has stated that this does not constrain plans for PGS deployment, since current plans do not come near the limits.[9] Nonetheless, in December 2010, Russian military experts indicated that the forthcoming S-500 missile defense system would include anti-hypersonic defenses.[10]
On 18 November 2011, the first Advanced Hypersonic Weapon (AHW) glide vehicle[11] was successfully tested by the U.S. Army Space and Missile Defense Command, as part of the Prompt Global Strike program. The missile was launched from the Pacific Missile Range Facility in Hawaii, and struck a target at the Reagan Test Site on Kwajalein Atoll, over 3,700 kilometres (2,300 mi) away, in under 30 minutes.[12] The prototype, which incorporated technologies developed by Sandia National Laboratories, was used to gather data to assist the development of future hypersonic warheads.[13]