The US Navy has now deployed the new W76-2 low-yield Trident submarine warhead. The first ballistic missile submarine scheduled to deploy with the new warhead was the USS Tennessee (SSBN-734)…The W76-2 warhead was first announced in the Trump administration’s Nuclear Posture Review (NPR) unveiled in February 2018. There, it was described as a capability to “help counter any mistaken perception of an exploitable ‘gap’ in U.S. regional deterrence capabilities,” a reference to Russia. The justification voiced by the administration was that the United States did not have a “prompt” and useable nuclear capability that could counter – and thus deter – Russian use of its own tactical nuclear capabilities…
We estimate that one or two of the 20 missiles on the USS Tennessee and subsequent subs will be armed with the W76-2, either singly or carrying multiple warheads. Each W76-2 is estimated to have an explosive yield of about five kilotons.* The remaining 18 missiles on each submarine like the Tennessee carry either the 90-kiloton W76-1 or the 455-kiloton W88. Each missile can carry up to eight warheads under current loading configurations…
The National Nuclear Security Administration (NNSA) has further explained that the “W76-2 will allow for tailored deterrence in the face of evolving threats” and gives the US “an assured ability to respond in kind to a low-yield nuclear attack.”
In 2018 the NATO alliance, joined by Sweden and Finland, held Trident Juncture, its largest exercise since the end of the cold war, in Norway. That involved the first deployment of an American aircraft-carrier in the Arctic Circle for three decades. Western warships have been frequent visitors since. On May 1, 2020 a “surface action group” of two American destroyers, a nuclear submarine, support ship and long-range maritime patrol aircraft, plus a British frigate, practised their submarine hunting skills in the Norwegian Sea.
Such drills are not unusual. But on May 4, 2020 some of those ships broke off and sailed further north into the Barents Sea, along with a third destroyer. Although American and British submarines routinely skulk around the area, to spy on Russian facilities and exercises covertly, surface ships have not done so in a generation. On May 7, 2020 Russia’s navy greeted the unwelcome visitors by announcing that it too would be conducting exercises in the Barents Sea—live-fire ones, in fact. On May 8, 2020… the NATO vessels departed.
It is a significant move. The deployment of destroyers which carry missile-defence systems and land-attack cruise missiles is especially assertive. After all, the area is the heart of Russian naval power, including the country’s submarine-based nuclear weapons. Russia’s Northern Fleet is based at Severomorsk on the Kola peninsula, to the east of Norway’s uppermost fringes.
Western navies are eager to show that covid-19 has not blunted their swords, at a time when America and France have each lost an aircraft-carrier to the virus. But their interest in the high north predates the pandemic. One purpose of the foray into the Barents Sea was “to assert freedom of navigation”, said America’s navy. Russia has been imposing rules on ships that wish to transit the Northern Sea Route (NSR), an Arctic passage between the Atlantic and Pacific that is becoming increasingly navigable as global warming melts ice-sheets . America scoffs at these demands, insisting that foreign warships have the right to pass innocently through territorial waters under the law of the sea. Although last week’s exercise did not enter the NSR, it may hint at a willingness to do so in the future.
On top of that, the Arctic is a growing factor in NATO defence policy. Russia has beefed up its Northern Fleet in recent years…Russian submarine activity is at its highest level since the cold war…Ten subs reportedly surged into the north Atlantic in October 2019 to test whether they could elude detection….Russia’s new subs are quiet and well-armed. As a result, NATO’s “acoustic edge”—its ability to detect subs at longer ranges than Russia—“has narrowed dramatically.”
Russia primarily uses its attack submarines to defend a “bastion”, the area in the Barents Sea and Sea of Okhotsk where its own nuclear-armed ballistic-missile submarines patrol. A separate Russian naval force known as the Main Directorate of Deep-Sea Research (GUGI, in its Russian acronym) might also target the thicket of cables that cross the Atlantic.
The challenge is a familiar one. For much of the cold war, NATO allies sought to bottle up the Soviet fleet in the Arctic by establishing a picket across the so-called GIUK gap, a transit route between Greenland, Iceland and Britain that was strung with undersea listening posts….The gap is now back in fashion and NATO is reinvesting in anti-submarine capabilities after decades of neglect. America has stepped up flights of P8 submarine hunting aircraft from Iceland, and Britain and Norway are establishing P8 squadrons of their own. The aim is to track and hold at risk Russian nuclear subs as early as possible, because even a single one in the Atlantic could cause problems across a large swathe of ocean.
But a defensive perimeter may not be enough. A new generation of Russian ship-based missiles could strike NATO ships or territory from far north of the GIUK gap, perhaps even from the safety of home ports. “This technological development represents a dramatically new and challenging threat to NATO forces…. Similar concerns led the Reagan administration to adopt a more offensive naval posture, sending forces above the gap and into the maritime bastion of the Soviet Union.
Excerpts from Naval Strategy: Northern Fights, Economist, May 16, 2020
The INS Arihant, India’s first nuclear-powered submarine armed with ballistic missiles (SSBN, in military jargon)… is a 6,000-tonne boat that will provide India with the third leg of its nuclear “triad”—it already has land- and air-launched nukes….India believes SSBNs are a vital part of its nuclear strategy, which forswears the first use of nuclear weapons….Because they can readily avoid detection, SSBNs can survive a surprise attack and thus ensure India’s ability to launch a retaliatory “second strike”….Some nuclear theorists argue that submarine-based deterrents promote peace by making the other side more frightened to attack first. …
China is ahead of the game. It has a fleet of four second-generation Jin-class SSBNs and is testing JL-2 missiles to install in them. These weapons have a range of 7,400km (4,600 miles)—too short, for now, to reach the American mainland from the relative safety of the South China Sea. Pakistan, for its part, is in the early stages of a lower-cost approach. This involves arming diesel-powered subs with nuclear-armed cruise missiles with a range of 700km.
A more immediate worry to India is Pakistan’s development and deployment of smaller “tactical” nuclear weapons for use on the battlefield. These may make it more likely that any war between India and Pakistan will go nuclear. They also increase the risk of Pakistan’s weapons being used accidentally—or falling into the hands of extremists (such weapons are under the control of lower-level commanders whose professionalism and loyalty may be dubious)….
India says it will not develop battlefield nukes of its own. Instead, it will rely on the threat of massive retaliation against any use of nuclear weapons by Pakistan. Still, it may be another decade before India has a fully-fledged sea-based deterrent. Arihant’s Russian nuclear-power generator is unsuited to long patrols. Initially, the sub is due to be armed with the K-15 missile, with a range of 750km—not enough to reach big cities in northern Pakistan. Striking Chinese ones would be harder still.
Asian Nuclear Weapons: What Lurks Beneathh, Economist, Feb. 6, 2016, at 36