Why bombers are the most flexible leg in the nuclear triad.
The ability to launch retaliatory strikes in response to nuclear aggression is the foundation of America’s nuclear deterrence strategy. Since the 1960s, a triad of intercontinental ballistic missiles (ICBM), ballistic missile submarines carrying submarine-launched ballistic missiles (SLBM), and nuclear-capable bomber aircraft underpinned this strategy. Today, the United States Air Force’s B-52H and B-2 bombers are the most flexible leg of the triad and are highly survivable once they are generated and ready to sortie from their air bases within minutes. Beginning in the mid-2020s, the next-generation B-21 “Raider” stealth bomber will join the inventory, eventually replacing the Air Force’s B-2s and conventional-only B-1B bombers.
Air Force B-52Hs have been operational since the early 1960s and will remain in the force until at least 2040. Originally designed as high-altitude bombers capable of delivering nuclear gravity bombs over intercontinental ranges, B-52s modified to carry conventional weapons played a critical role during the Vietnam conflict and in every major air campaign since. For instance, B-52s flew an average of 50 sorties per day and delivered 40 percent of all the weapons dropped by coalition forces during Operation Desert Storm against Iraq in 1991.
While B-52Hs can deliver a variety of short-range weapons such as Joint Direct Attack Munitions against targets in permissive threat environments, they are not stealth aircraft and must launch long-range standoff weapons against targets located in contested areas covered by modern integrated air defense systems (IADS). A single “BUFF,” as B-52s are nicknamed, can carry up to twenty 2,000-pound class Joint Air-to-Surface Standoff Missiles (JASSMs) that are designed to penetrate contested areas, and an extended range JASSM-ER will allow them to strike from standoff distances of 500 nautical miles or more. B-52Hs are stationed at Minot Air Force Base, N.D., and at Barksdale Air Force Base, La.
At this time, B-52Hs are the only USAF bombers that can carry nuclear-capable air-launched cruise missiles (ALCMs). The Air Force began developing the AGM-86B ALCM in the 1970s to improve the B-52’s ability to strike targets defended by Soviet-era surface-to-air missiles and other threats. First fielded in 1982, with a projected service life of 10 years, AGM-86B ALCMs are subsonic, long-range weapons. A B-52H can carry up to 20 ALCMs armed with W80-1 warheads. Beginning in the late 2020s, the Air Force will replace its ALCMs with the long-range standoff (LRSO) weapon. The LRSO will carry a W80-4 nuclear warhead and have the ability to penetrate advanced IADS, operate in GPS-denied environments, and hold high-value targets at risk from significant standoff ranges. LRSOs will ensure B-52Hs remain a viable part of the triad well into the future.
USAF’s B-2 stealth bombers joined the force beginning in the early 1990s. B-2s have flying wing designs that decrease their radar and infrared signatures, reducing the probability they will be detected by enemy air defenses. The B-2’s design, radar-absorbent materials, onboard sensors to detect threats, secure connectivity, and ability to fuse information from multiple sources give it the ability to penetrate contested areas. B-2s can deliver large payloads of conventional and nuclear weapons on targets with precision in all weather conditions, and they are certified to carry B61-7/11 and B83 nuclear gravity bombs. Although these weapons will be retired in the mid-2020s, a life extension program will replace current B61 variants with the B61 Mod 12 that will have new and refurbished components, as well as a tail kit to improve its accuracy.
B-2s will soon be joined by next-generation stealth B-21s capable of penetrating future threat environments. Beginning in the mid-2020s, the Air Force intends to procure at least 100 B-21 aircraft that will be capable of carrying conventional weapons, the LRSO, and B61-12 gravity bombs.
Why Is the Bomber Force Relevant Today?
America’s global interests are now being threatened like never before. China and Russia pose security challenges that the United States has not confronted since the Cold War—some potentially existential in nature. At the same time, rogue states like North Korea and Iran have ballistic missiles and aspire to develop the ability to deliver nuclear warheads over long ranges, and non-state actors continue to plot attacks against the U.S. and its allies.
The concurrency of these threats has stretched America’s military resources thin. With vital interests on the line, the Department of Defense (DOD) will modernize the forces and capabilities that are most critical to executing the 2018 National Defense Strategy. Weapon systems like USAF bombers that are capable of attacking targets with conventional or nuclear weapons over global ranges are a top priority. Long-range strike bombers, when paired with an effective campaign strategy aimed at vital targets, are one of the most effective tools available to America’s commanders. Unlike most elements of the joint force, bombers with large payloads of conventional weapons can respond within hours to strike targets located inside contested areas. This early firepower will be essential to achieving time-sensitive objectives for theater commanders—a realistic scenario could require them to rapidly halt Chinese or Russian aggression against an American ally.
The Air Force’s nuclear-capable bombers also complement other legs of the triad. B-2s and B-52Hs can generate to alert status within a matter of hours, disperse to multiple airfields to reduce their vulnerability to nuclear strikes, or deploy overseas to reassure allies and demonstrate resolve in a crisis. Unlike SLBMs and ICBMs, bombers can be launched and recalled without employing their nuclear weapons, giving U.S. National Command Authorities another means to signal resolve. Bomber crews can modify their mission profiles, change targets in flight as directed, and determine if their weapons should be withheld. Bombers can also regenerate after a sortie to prepare for follow-on missions or to reestablish deterrence after an attack. Penetrating bombers are the only triad leg capable of locating and attacking highly mobile or relocatable targets such as ICBM transporter- erector-launchers. This is a key reason the Air Force chose to procure the B-21.
The Air-Breathing Leg of the Triad
After three decades of cuts and delayed modernization, the B-21 program will create a future bomber force that is appropriately sized and has the right mix of penetrating and standoff strike capabilities needed by U.S. combatant commanders. Although there is strong national support for the B-21, a few critics continue to question the need for it. Factors contributing to DOD’s decision to procure the B-21 generally fall into two categories. First, USAF’s bomber force is too small to meet the demands of the National Defense Strategy, and, second, there is a need for a next-generation bomber that can penetrate future contested operational environments.
The Air Force’s total inventory of 76 B-52Hs, 62 B-1Bs, and 20 B-2s is the oldest and smallest bomber fleet the service has ever operated. Since the Cold War, the bomber force declined from about 400 aircraft to 158 total tails, primarily due to DOD’s desire to generate savings and its belief that a smaller bomber force would suffice for limited conventional conflicts with rogue states such as Iran and North Korea. Both rationales were behind the Department of Defense’s 1997 decision to cap the B-2 program at 21 aircraft instead of buying all 132 B-2s required by the Air Force.
The long ranges, large payloads, and multi-mission capabilities of bombers are exactly the kind of attributes theater commanders need to deter aggression. However, multiple studies have concluded the current bomber force cannot generate enough conventional strike sorties for a single major conflict with a peer adversary plus sustain nuclear deterrence simultaneously, and thus recommended the Air Force grow the inventory as quickly as possible. Furthermore, B-52Hs and B-1Bs designed to penetrate Cold War-era Soviet air defenses are not capable of operating in areas defended by advanced IADS, and the stealth B-2 force is far too small. In short, a larger and more balanced mix of penetrating and standoff bombers is needed. Recent Air Force Chief of Staff Gen. David L. Goldfein said the future force that wins will have “a combination of that which works from inside and that which works from outside. … [A] balance [of long-range penetrating and standoff strike forces].” Goldfein also testified, “Our assessment—and that’s been backed up by independent assessments—that a moderate risk force is 220 bombers, of which 145 would be B-21s.” Finally, DOD’s 2018 Nuclear Posture Review determined that delays in procuring B-21s would “reduce the ability of our strategic forces to penetrate adversary air defenses, limit the diversity of our response options, and compromise our ability to send the visible deterrence and assurance signals for which strategic bombers are particularly well-suited.”
The need for aircraft with next-generation stealth such as the B-21 is another recurring issue. Stealth skeptics typically point to advances in computing power, the increased accuracy of radars that operate in low-frequency bands, and other air defense improvements that could erode America’s stealth asymmetric advantage. Those who believe stealth is not worth the investment often fail to consider that DOD’s development of next-generation stealth technologies continues to outpace advances in defensive systems. This is a key reason the Defense Department decided to acquire the B-21. Aircraft stealth is the result of a multi-pronged approach that includes minimizing aircraft signatures in multiple bands of the electromagnetic spectrum (low observability) and at all aspects. B-21s will have next-generation radar-absorbent materials, increased processing power to fuse information from onboard sensors and external sources, and low probability of intercept/low probability of detection data links that will maximize opportunities to collaborate with other weapon systems. All-aspect, low observability in multiple frequency bands combined with these other capabilities will enable B-21s to penetrate adversary defenses well into the future.
Another critical point for Airmen to stress is that stealth does not make aircraft invisible to enemy sensors—it denies an enemy information required to launch a successful intercept. Many who view stealth as a waning advantage fail to understand this. Given that information dominance is increasingly critical to success in modern warfare, the need for stealth will actually grow in importance, not diminish.
Critics have also questioned the need to replace the ALCM, arguing the LRSO will be a redundant or even a destabilizing capability. Although there are many reasons for why the LRSO is needed, DOD most frequently cites concerns over the ALCM’s future viability, its reduced survivability in modern threat environments, and implications to U.S. nuclear deterrence as a whole if it is not fielded.
The AGM-86B ALCM is the only air-launched nuclear cruise missile in the U.S. military’s inventory. Although it was designed in the mid-1970s to have a planned service life of 10 years, life extension programs will keep ALCMs in the inventory until approximately 2030. Similar to other USAF nuclear weapon systems, there is a limit to how long ALCMs can be sustained. Former USSTRATCOM Commander Gen. John E. Hyten testified to Congress that ALCMs have “sustainability and viability issues from age-related material failures, advancing adversary capabilities and diminishing manufacturing sources. Parts and materials designed for a 10-year service life are now 35 years old, and are obsolete,” and the ALCM’s service life extension programs “cannot keep pace with the rate of discovery of deficiencies.” Moreover, required testing will reduce the number of operationally available ALCMs below the required level by the year 2030.
Concern over the ALCM’s ability to penetrate increasingly lethal Soviet air defenses caused the Air Force to initiate a program to replace its ALCMs shortly after they became operational. The resulting AGM-129 advanced cruise missile (ACM) had stealth coatings, forward-swept wings, and other design features to improve its ability to penetrate contested areas. For budgetary and other reasons, DOD terminated ACM production early, did not replace its ALCMs, and eventually retired its ACMs. If the ALCM is not replaced by the LRSO, its inability to penetrate would deprive the air-breathing leg of the triad of a means of conducting standoff nuclear strikes. In effect, this would eliminate B-52Hs as a viable part of the triad since these non-stealth aircraft must use standoff weapons to strike into contested areas.
Critics assert cruise missiles are destabilizing capabilities that increase the chance of a nuclear exchange since enemies cannot determine if they carry a conventional or nuclear warhead. The truth is that bombers with nuclear cruise missiles may be the most stabilizing element of the triad. As the 2008 Schlesinger Commission concluded, “If this standoff capability is allowed to disappear, then the ability to signal strategic capability through the generation and dispersal of B-52s will be compromised.” The Department of Defense has fielded multiple cruise missile variants in the past without Russian and Chinese objections, and China and Russia have done the same without concern they could be destabilizing.
Conclusion
Air Force bombers provide options to U.S. combatant commanders that are unmatched by other conventional or nuclear-capable forces. A right-sized force of dual-capable B-52Hs and B-21s will be able to deter nuclear threats to the homeland and simultaneously conduct large-scale conventional strike operations during a major conflict with a peer adversary. No other leg of the triad will have this multi-mission capability, which is a key reason that DOD supports growing the bomber force to at least 220 total aircraft by buying B-21s. USAF nuclear-capable bombers offer options to signal America’s resolve in ways that cannot be matched by other triad capabilities, and they can recover after strikes to help reestablish deterrence or prepare for follow-on operations.
The Air Force’s ability to provide these capabilities will diminish if much-needed modernization programs are prematurely ended or delayed, as they have been in the past. Without next-generation B-21s, the bomber force will lack the capacity needed to execute the national defense strategy and will lose its ability to conduct long-range penetrating strikes into contested environments. This would greatly simplify an enemy’s air and missile defense challenge. The LRSO is also needed to ensure B-52Hs remain a viable part of the triad capable of holding at risk targets located in contested areas. According to former Vice Chairman of the Joint Chiefs of Staff Gen. Paul J. Selva (Ret.), LRSO will complicate an enemy’s air defense challenge by “presenting many more small and low-observable penetrators than a single bomber with gravity weapons can present on its own. In combination with a penetrating bomber, LRSO will significantly reduce a potential adversary’s ability to achieve sanctuary within his borders.”
