A nuclear triad is a three-pronged military force structure of global-range land-based intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (SLBMs), and strategic bombers with nuclear bombs and missiles. More broadly, it can sometimes be used to mean any nuclear force with land, sea, and air basing, and more limited range. Countries build nuclear triads to eliminate an enemy's ability to destroy a nation's nuclear forces in a first-strike attack, which preserves their own ability to launch a second strike and therefore increases their nuclear deterrence.
Four countries are known to have a nuclear triad: the United States, Russia, India, and China. The US and the USSR (the predecessor state to Russia) acquired triads as part of the Cold War's nuclear arms race, operationalizing SLBMs during the 1960s. Meanwhile, India achieved one in 2018, and China did so in 2020.
France had a nuclear triad, but in 1996 France abandoned its strategic bombers, IRBM underground silo-based S3 missiles, and Hadès SRBMs. Despite becoming the third nuclear power in 1952, the United Kingdom has never operated a triad.
Israel likely possesses weapons in a triad structure, but lacks true strategic range in all three 'legs.'
Components of a strategic nuclear triad
While traditional nuclear strategy holds that a nuclear triad provides the best level of deterrence from attack, most nuclear powers do not have the military budget to sustain a full triad. The only two countries that have successfully maintained a strong nuclear triad for most of the nuclear age are the United States and Russia. Triads include: Bomber aircraft: Aircraft carrying nuclear weapons including gravity bombs, or air-launched ballistic or cruise missiles (ALBMs or ALCMs), for use against ground or sea targets. Land-based missiles of various ranges (GLCMs, SRBMs, MRBMs, IRBMs or ICBMs): Delivery vehicles powered by a liquid or solid-fueled rocket that primarily travel in a ballistic (free-fall) trajectory. Ballistic missile submarines (SSBNs): Nuclear missiles launched from ships or submarines (SLBMs, SLCMs). They are classified under an umbrella of vessels and submarines that are capable of launching a ballistic missile.
The triad enables a nation to deliver a nuclear attack by air, land, or sea. The United States built its triad to maximize the probability that it could retaliate for a first strike. Having three legs also protects against new technology, like an enemy missile-defense system. It also gives the commander-in-chief the flexibility to use different types of weapons for the appropriate strike while also maintaining a reserve of nuclear weapons safe from a counter-force strike.
Strategic bombers are the first leg of the triad. They have greater flexibility in their deployment and weaponry, and can be quickly deployed and recalled in response to last-minute decisions. Since bombers are recallable, sending them away from a potential target is a highly visible way of demonstrating to enemies and allies that a nation wants to resolve a fight, thus preventing war. Some disadvantages include confusion on the type of payload. Bombers can hold both nuclear and conventional weapons. During an event, an enemy could suspect that a conventionally-armed bomber was actually carrying a nuclear weapon, encouraging the enemy to attack the bomber or make a nuclear strike. Furthermore, bombers that are scrambled might intensify tension and arouse suspicion of an upcoming nuclear strike. Bombers can serve as both a first- and second-strike weapon. For example, a bomber armed with AGM-129 ACM missiles could be classified as a first-strike weapon and bombers that are classified as needing an aerial refueling aircraft to strike targets would constitute as a second-strike weapon. If dispersed in small airfields or aboard an aircraft carrier, they can reasonably avoid a counterstrike giving them regional second-strike capacity. Aircraft such as the Mirage 2000, F-15E, A-5 Vigilante, Sea Harrier, or FB-111 were tasked with land or sea-based strategic nuclear attack missions. Bombers that contain an aerial refueling fleet support intercontinental strategic operations for both heavy bombers and smaller aircraft. It also makes it possible for bombers to be alert and on standby, making these airborne assets nearly impossible to eliminate in a first strike. Strategic bombers generally fall into two categories: Stealth or supersonic bombers capable of delivering nuclear gravity bombs with low risk of interception. Operational examples are the US stealth B-2 Spirit and Russian supersonic Tu-160. Future examples are the US stealth B-21 Raider, Chinese stealth H-20, and Russian stealth PAK DA. Bombers which carry long-range nuclear weapons, typically air-launched cruise missiles, and more rarely air-launched ballistic missile. Operational examples include the US B-52 Stratofortress and Russian Tu-95MS. Intercontinental ballistic missiles (ICBMs) allow for a long-range strike launched from a controlled environment. These missiles can also be launched, and reach targets, faster than the other legs of the triad. Because firing an ICBM is an unmistakable act, they provide stronger clarity about when a country is under attack and who the attacker is. ICBMs launched from fixed positions, like missile silos, are vulnerable to a first strike, though their interception once aloft is substantially difficult. This vulnerability, along with their general inability to be forward-deployed, weakens ICBMs' contribution to nuclear deterrence compared to bombers or submarines. Some ICBMs are mobile by either rail or road. Medium-range ballistic missiles and ground-launched cruise missiles were assigned to strategic targets but bilaterally forbidden by the United States and Russia from 1987 to 2019. Submarine-launched ballistic missiles (SLBMs) maintain a greater chance of surviving a first strike, giving the commander a second-strike capability. Nuclear submarines do not have fixed locations like missile silos or airfields, and they are more easily concealed than bombers. Because of their low detectability and quick mobility, SLBMs are almost invulnerable at sea. A disadvantage of SLBMs is that it might be unclear whether the destruction of a nuclear submarine was the result of an accident or an attack. Also, maintaining a force of nuclear submarines can be very expensive. Tactical nuclear weapons, also known as non-strategic nuclear weapons, are used in air, land and sea warfare. Their primary use in a non-strategic war-fighting role is to destroy military forces in the battle area. But, depending on the target in today's nuclear age, they are not counted toward triad status because of the possibility that many of these systems could be used as strategic weapons. During the Cold War, it was easy to point out which nuclear weapons were tactical. Each type of weapon had different capabilities that were better suited for different missions. Air-to-air missiles, rockets, surface-to-air missiles, small air-to-ground rockets, bombs, and precision munitions have been developed and deployed with nuclear warheads. Ground forces have included tactical nuclear artillery shells, surface-to-surface rockets, land mines, medium and small man-packable nuclear engineering demolition charges, and even man-carried or vehicle-mounted recoilless rifles. Naval forces have carried weapons that include nuclear-armed naval rockets, depth charges, torpedoes, and naval gunnery shells.
Country comparison
Triad powers
China
Unlike the United States and Russia, where strategic nuclear forces are enumerated by treaty limits and subject to verification, China—a nuclear power since 1964—is not subject to these requirements. Instead, China currently has a triad structure smaller than those of Russia and the United States. China's nuclear force is closer in number and capability to those of France or the United Kingdom, making it much smaller than the American or Russian triads. The Chinese nuclear force consists mainly of land-based missiles, including ICBMs, IRBMs, tactical ballistic missiles, and cruise missiles. Unlike the US and Russia, China stores large numbers of its missiles in massive tunnel complexes; U.S. Representative Michael Turner, referring to 2009 Chinese media reports, said "This network of tunnels could be in excess of 5,000 kilometers (3,110 miles) and is used to transport nuclear weapons and forces. The Chinese Army Newsletter calls this system of tunnels the Underground Great Wall of China. China's nuclear warheads are believed to be stored in a central storage facility and not with the launchers.
China currently has one Type 092 submarine which is currently active with JL-1 Submarine Launch Ballistic Missiles (SLBM) according to the Office of Naval Intelligence. In addition, the People's Liberation Army Navy (PLAN) has deployed four newer Type 094 submarines and plans to deploy up to eight of these Jin-class SSBN by the end of 2020. The Type 094 fleet uses JL-2 and JL-3 SLBMs. The Chinese fleet carried out a series of successful JL-2 launches in 2009, 2012 and 2015. The United States expected the 094 SSBN to carry out its first deterrent patrol in 2015 with the JL-2 missiles active. According to Pentagon report, China began to ensure that one nuclear-armed ballistic missile submarine would always on stand by for deterrence around 2023.
There is an aged, upgraded bomber force consisting of Xian H-6s with an uncertain nuclear delivery role. The PLAAF has a limited capability fleet of H-6 bombers modified for aerial refueling as well as forthcoming Russian Ilyushin Il-78 aerial refueling tankers. China has also introduced newer and modernized H-6 variants, including the H-6K and H-6N. The H-6K has enhanced capabilities such as launching long ranged cruise missiles like the CJ-10, while the H-6N is capable of carrying the JL-1. In addition to the H-6 bomber, there are numerous tactical fighter and fighter-bombers such as the J-16, J-10, JH-7A and Su-30 that are all capable of carrying nuclear weapons. It is estimated that China maintains an arsenal of about 250 nuclear warheads and that it has produced about 610 nuclear warheads since becoming a nuclear power in 1964. China is phasing out old liquid-fueled ballistic missiles and arming several new solid-fueled missiles. In the same estimate, it is believed that China has a small inventory of air-delivered nuclear bombs. As well as production is more than likely underway of new warheads for missiles to arm the Jin-class submarines.
The U.S. intelligence community expects that China will increase their total number of warheads and long-range ballistic missiles from about 50 to exceed 100 in the next 15 years, this calculation has been sliding since 2001. Since the end of the Cold War, China is suspected to have doubled their nuclear arsenal, while the other nuclear powers under the Treaty on the Non-Proliferation of Nuclear Weapons have cut their forces in half. A Pentagon report raises the possibility of China moving towards a more vigorous nuclear doctrine that will allow first use of nuclear weapons in times of war. While it is not expected that China will give up the current "no first use" policy in the near future, the Pentagon report raises concerns that "this issue has been and will continue to be debated in China. It remains to be seen, how the introduction of more capable and survivable nuclear systems in greater numbers will shape the terms of this debate or affect Beijing's thinking about nuclear options in the future."
India