India joined an elite club of nations on March 11 with the first successful flight test of an Agni-5 ballistic missile armed with multiple independently targetable re-entry vehicles (MIRVs). Only the permanent members of the United Nations Security Council -- the United States, the United Kingdom, Russia, China, and France -- are confirmed to have operational missiles that use MIRVs.
Named Mission Divyastra, the flight test of India's MIRV technology was carried out by the Defence Research and Development Organisation (DRDO) from Dr APJ Abdul Kalam Island in Odisha. According to a government release, various telemetry and radar stations were used to track and monitor the multiple re-entry vehicles that were carried by the Agni-5 missile, and the mission was a success based on the designated parameters.
What are MIRVs?
MIRV technology was originally developed in the early 1960s, during the height of the Cold War between the United States and the erstwhile Soviet Union. MIRVs allow a single missile to deliver multiple nuclear warheads to separate targets, while a traditional missile carries only one warhead and is limited to one target. With MIRV technology, each warhead is carried in a separate re-entry vehicle and can be programmed to hit a separate target. A missile armed with MIRVs can release its warheads at different speeds and even in different directions. And how far can these different targets be? According to The Center for Arms Control and Non-Proliferation, a Washington-based research organisation, at least some MIRV-equipped missiles can hit separate targets that are as far apart as 1,500 kilometres.
Diagram depicting the different stages of a Minuteman III missile from launch to detonation, including deployment of MIRVs. Image credit: Fastfission (Wikipedia)
Why is MIRV success important?
Going by the initial reports, the Agni-5 system's new ability to strike multiple targets with one missile might appear to be the most important outcome of Mission Divyastra, but a deeper look at how MIRVs work throws up an even more important achievement. MIRVs make defending the intended targets much more difficult for the adversary nation. As explained by The Center for Arms Control and Non-Proliferation: While MIRVs were not initially meant to defeat ballistic missile defence (BMD) systems -- a network of sensors and interceptor missiles that can destroy an incoming ballistic missile or warhead before it can hit its target -- they are much more difficult to defend against than traditional missiles. Thus, they are effective BMD countermeasures. An ANI report that cited defence sources backs this up. According to the report, MIRV technology will make an Agni-5 missile more difficult to intercept because its warheads will approach their intended targets along with the mother vehicles and multiple decoys. An adversary's BMD sensors will have to cut through the resultant clutter and the interceptor missiles might get overwhelmed. Multiple missiles armed with MIRVs could even make a comprehensive BMD system cost-prohibitive for the adversary. Given that China has BMD capabilities, MIRVs will boost the Agni-5's chances of hitting its targets successfully.
How many nuclear warheads can Agni-5 MIRV carry?
The short answer is that we don't know the maximum number of MIRVs an Agni-5 could carry operationally. But, details emerging from the March 11 test provide some clues. Citing unnamed defence sources,
ANI has reported that an Agni-5 missile armed with MIRVs would be able to strike at least three different targets spread over a large area. The report also said that the missile's warheads would be accompanied by multiple decoys as they close in on their intended targets. This gives weight to the other claim attributed to the defence sources: The number of warheads carried by the Agni-5 missile can be increased if required. So, the Agni-5 MIRV can carry at least three nuclear warheads, if it also wants to use decoys alongside to make the interception of these warheads more difficult.
According to Business Standard's Ajai Shukla, during the Mission Divyastra test, the Agni-5 missile was carrying between four to six dummy warheads. Given that this was just the first test of an Agni-5 with MIRVs, there is no confirmation that six would be the maximum number of warheads the missile could carry operationally. But, between three-six warheads seems to be the only available answer for now.
What is Agni-5's actual range?
Officially, the Agni-5 is an intermediate-range ballistic missile (IRBM), with an acknowledged range of 5,000 kilometres. However, various sources and media reports also describe it as an intercontinental ballistic missile (ICBM). An ICBM has a range greater than 5,500 kilometres. For their part, Chinese officials have always considered the Agni-5 to be an ICBM. They claim that the Agni-5's actual range is 8,000 kilometres.
So, what's the truth? Is the Agni-5 an IRBM or an ICBM? Well, one way to extend the range of the 50-tonne Agni-5 missile would be to reduce its weight. And it seems that that process has been underway for sometime. In December of 2022,
India Today had reported that the Agni-5 missile had become capable of striking targets beyond 7,000 kilometres because its weight had been reduced significantly. According to the report, defence officials had said that a weight reduction of over 20 per cent had been achieved and thus, the nuclear-capable Agni-5 ballistic missile could strike targets beyond 7,000 kilometres if the government wanted it to. Still, the government has not confirmed this to be the Agni-5's real range.
However, writing for Business Standard after the success of Mission Divyastra, Ajai Shukla confirmed that the hydraulic actuators in Agni-5's first stage have been replaced by electro-mechanical actuators, which save weight and already equip the missile's second and third stages. According to Shukla, going ahead, the Agni-5 could become significantly lighter than at present.
Does Pakistan also have MIRV tech?
Pakistan has also been trying to develop MIRV technology. In January of 2017, Pakistan conducted the first flight test of its Ababeel surface-to-surface ballistic missile, which has a maximum range of 2,200 kilometres. At that time, Pakistan had claimed that the Ababeel was capable of delivering multiple nuclear warheads using MIRV technology. An official press release had added: "The test flight was aimed at validating various design and technical parameters of the weapon system." In October of 2023, Pakistan again tested the Ababeel missile, with the Pakistani military's media wing stating that the test was "aimed at re-validating various design, technical parameters and performance evaluation of different sub-systems" of the missile. At no point was there explicit mention that the MIRV capability had been successfully demonstrated.
However, in his March 2018 testimony to the US Congress, Robert Ashley, the then director of the US' Defense Intelligence Agency, had said: "In January 2017, Pakistan conducted the first test launch of its nuclear-capable Ababeel ballistic missile, demonstrating South Asia's first MIRV payload." Back in 2018, at least American intelligence sources were of the opinion that Pakistan either possessed or was close to possessing the MIRV technology.
What could come next after MIRV success?
Submarine-launched ballistic missiles (SLBMs) can benefit from MIRVs the most. Submarines have limited real estate and can carry only a handful of missiles. Moreover, nuclear-powered submarines that carry ballistic missiles are expensive and difficult to field in considerable numbers. At the same time, they have a higher chance of surviving an initial nuclear attack and responding in kind. Thus, while no official indication has been given so far, increasing the number of targets that India's SLBMs could hit would be the next logical step.