India successfully tested a submarine-launched ballistic missile (SLBM) from its indigenous INS Arihant nuclear ballistic missile submarine (SSBN), reaffirming its place in an elite club of nations with the ultimate in strategic nuclear deterrence.

On October 14, the Indian Ministry of Defence (MoD) announced that the INS Arihant, which means “destroyer of enemies” in Sanskrit, successfully tested an SLBM, firing the missile at a predetermined range and impacting the designated target area at the Bay of Bengal with “very high accuracy,” The Indian Express reported.

“All operational and technological parameters of the weapon system have been validated,” said the Indian MoD in a press statement.

“The successful user training launch of the SLBM by INS Arihant is significant to prove crew competency and validate the nuclear-powered ballistic missile submarine (SSBN) program, a key element of India’s nuclear deterrence capability,” the statement said. “A robust, survivable, and assured retaliatory capability is in keeping with India’s policy to have ‘Credible Minimum Deterrence’ that underpins its ‘No First Use’ commitment.”

This successful launch builds on previous 2018, 2016 and 2015 tests. Although India did not identify the exact missile in the latest test, it was most likely the Sagarika SLBM. According to Global Security, the Sagarika has a range of 700 kilometers and can carry a 1-ton warhead. It notes that India tested unarmed Sagarika missiles from the INS Arihant in 2016 and 2015.

As of 2022, the Observer Research Foundation (ORF) reports that India operates three Arihant-class SSBNs, with the lead boat INS Arihant commissioned in 2016 and the soon-to-be INS Arighat launched in 2017 and still undergoing advanced sea trials. India reportedly launched the third boat last November with little public fanfare.

ORF notes that India requires at least four SSBNs and enough SLBMs to maintain a credible undersea nuclear deterrent, although technical difficulties may delay this project. Such challenges include miniaturizing nuclear reactors for naval use and ensuring enough room for missiles aboard the submarines.

In addition, ORF notes that the Sagarika’s relatively short range of 700 kilometers compared to other SLBMs means the INS Arihant must manoeuvre close to enemy waters to launch the missiles. This necessity exposes the submarine to enemy attack and negates the logic of having an undetectable undersea nuclear deterrent.

However, India is developing longer-ranged SLBMs to eliminate the handicap. The Hindu reported that India tested the 3,500-kilometer range K-4 SLBM in 2020. Quoting an anonymous source, The Hindu stated that “the test was conducted from a submerged pontoon and has met the desired parameters,” with a pontoon simulating a submarine launch.

The anonymous source also stated that the most challenging part of the test was ejecting the missile from a submerged platform and that the K-4 has a smaller Circular Error Probability (CEP) than China’s missiles, meaning that it has superior accuracy.

India’s SLBM test comes as arch-rival Pakistan and long-term threat China are diversifying their nuclear launch platforms and boosting their respective nuclear arsenals.

Pakistan's Dilemma

In a 2020 article in South Asian Voices, Sufian Ullah notes that Pakistan’s current undersea nuclear capability is limited to the Babur-III submarine-launched cruise missile (SLCM) with a range of 450 kilometers, and five Agosta-class conventional submarines.

Ullah also notes that Pakistan’s limited landmass and the threat of an Indian hard counterforce strike against Pakistan’s small, land-based nuclear arsenal have compelled the latter to increase the survivability of its nuclear force by deploying more weapons at sea.

To that end, Pakistan has made initial steps in establishing a sea-based nuclear deterrent. For example, a 2019 article from the Journal for Peace and Nuclear Disarmament notes that in 2012 Pakistan established a Naval Strategic Force Command, indicating an intention to deploy nuclear weapons at sea.

Furthermore, in 2018, Pakistan announced the successful underwater test launch of the Babur III SLCM, with its Inter-Services Public Relations (ISPR) describing the result as the “successful attainment of a second-strike capability.”

The same article mentions that Pakistan may want to build its own SSBNs but such ambitions may be too lofty for Pakistan’s limited technical expertise. It notes that Pakistan may request training on and lease China’s sole aging 1980s Type 092 SSBN, which is slated to be replaced by newer Type 094 boats.

That move would echo India’s 2019 lease of a Russian Akula-II nuclear-powered attack submarine (SSN) to learn how to operate such sophisticated vessels.

The article also mentions that Pakistan may have begun preliminary work on a submarine nuclear reactor, with the Pakistan Atomic Energy Commission (PAEC) working on such a prototype since 2001. However, it says that Pakistan’s efforts may be limited to a land-based prototype and that Pakistan may seek technical assistance from China.

However, Pakistan is now on the brink of economic collapse due to declining foreign currency reserves and hyper inflation. The country's debt has jumped to a record high, given these extenuating factors it is only a matter of conjecture as to how Pakistan will be able to fund such high-cost vanity projects.

India’s current nuclear capabilities may be insufficient to create the perception of a credible threat in the minds of China’s defence planners, failing the very deterrent purpose for which they were created.

In a 2020 paper for the Carnegie Endowment for Regional Peace, Toby Dalton and Tong Zhao mention that China maintains a relaxed attitude towards India’s nuclear arsenal, even as the latter has missiles that can reach deep into China, has deployed SSBNs, tested an anti-satellite missile and has developed Multiple Independent Re-Entry Vehicle (MIRV) capability for its ballistic missiles.

They also note that India’s nuclear arsenal failed to deter China in the 2020-2021 Himalayan clashes, which resulted in deaths and territorial losses for India.

Dalton and Zhao mention several reasons for China’s apparent confidence despite India’s nuclear arsenal. First, they note that China is confident that its system of governance is superior to India’s and that it will maintain and enhance its military and nuclear advantages to consistently stay ten years ahead of India.

They also mention that, despite their Himalayan border dispute, China-India relations remain broadly positive. Although China and India see each other as rivals, economic interdependence will prevent nuclear weapon use, they argue. In addition, Dalton and Zhao argue that China sees India’s nuclear arsenal as for general deterrence and prestige, and not for actual deployment.

However, they note that China’s efforts to modernize its nuclear arsenal vis-à-vis the US may start a negative feedback loop that can spill over to third parties such as India.

US attempts to modernize its nuclear arsenal, such as replacing the aging Minuteman-III land-based ballistic missile, developing the B-21 stealth bomber and Columbia-class SSBN.

China has recently developed its H-20 stealth bomber, Type 094 SSN and railway nukes. Given the uncertainty about China’s intentions and nuclear arsenal, India may be compelled by this perceived threat to modernize its nuclear weapons.

Nevertheless, India deems submarine-based nuclear weapons critical to its strategic security. In a separate article for The Indian Express, Sushant Kulkarni mentions that SSBNs like the INS Arihant allow for a nuclear second-strike capability, which he sees as necessary for a “credible nuclear deterrence.”

Kulkarni notes that India’s second-strike capability is guided by its “no-first-use” nuclear policy, which stipulates that India will only use nuclear weapons against a nuclear attack against Indian territory or Indian forces. He notes that a retaliation strike will be massive to achieve deterrence and inflict unacceptable damage, which is possible only through nuclear weapons.