India’s successful test of its Agni-V land-based intercontinental ballistic missile (ICBM) with multiple independently targetable re-entry vehicles (MIRV) last week represents a significant milestone in the nation’s nuclear ambitions.

While a veritable alphabet soup, MIRVed missiles are unique in that one missile carries multiple nuclear warheads in its nose cone, meaning one missile can strike multiple targets, and better evade local defences.

Put simply, while one traditional ballistic missile can strike one target, packing multiple independently targetable re-entry vehicles into a single missile (often plus decoys) means that a range of targets across hundreds of kilometres can be hit simultaneously. It provides the aggressor a better chance that some nuclear warheads will circumvent defensive measures.

In India’s case, it’s believed Agni-V could carry four or five warheads per missile, although no official number has been given. This was the tenth such launch of Agni-V since 2012, but it was the first to test India’s indigenously developed MIRV technology. More tests will be required before the capability can be deployed. The launch was lauded by Indian Prime Minister Narendra Modi.

MIRV technology is not new. The United States first deployed a MIRVed missile (Minuteman III) in 1970, developed to overwhelm Soviet anti-ballistic missile defences installed at the time. The British first deployed MIRVed missiles in 1982 (with American developmental assistance), the French in 1985, Soviets in 1988, and the Chinese in 2015. Pakistan’s MIRV technology is still under development, Israel is suspected to have it, and North Korea’s capability is still latent.

While last week’s successful test, which took place on Abdul Kalam Island in the Bay of Bengal, is a significant milestone, the technology will need further refinement before it can be deployed. However, the eventual technology, once deployed, will be a boost for the credibility of India’s nuclear arsenal.

Vis-à-vis China, Agni-V’s anticipated range of more than 5,000 kilometres means India could strike China’s mainland. However, more importantly, the MIRVed warheads mean India can be confident that its warheads will not just reach targets, but also evade any future missile defence system China deploys. Nuclear weapons require credibility to deter an aggressor, and India’s new MIRVed capability will provide this critical credibility.

Just as importantly, by MIRVing missiles, India can rapidly add immense firepower to its arsenal with limited missiles. While one non-MIRVed missile fires one warhead, by installing four or five warheads per missile, the devastating lethality of India’s stockpile commensurately increases. In addition, India’s numerous warheads need not be as accurate to be credible.

The test launch timing is also significant.

Taking place in the lead-up to India’s general election (commencing in April), this successful test demonstrates Modi and his Bharatiya Janata Party’s strong national security and defence credentials. Celebrated also is India’s ability to indigenously design and create this MIRV-capable warhead – indigenously built defence products being a key Indian defence priority. MIRVed warheads are immensely complex to design, build and test – largely in secret – requiring huge financial investment.

However, MIRVing missiles is widely viewed as destabilising, especially land-based missiles. MIRVed missiles become a high-value target, as destroying these assets in a first strike can radically reduce one’s ability to credibly respond. While the United States, for example, deploys MIRVed missiles deep underwater in submarines, which are largely undetectable and hard to strike, India’s future land-based MIRVed missiles will provide an attractive first strike target for any would-be aggressor.

While India pledged its “no first use” policy in 1998, meaning it would not initiate a nuclear weapon attack but only respond in retaliation, it has steadily developed and modernised its arsenal. This successful MIRV test is a substantial step forward to modernise its arsenal, build credibility and increase lethality. Telling will be whether India MIRVs its submarine-launched ballistic missiles in future, which would add lethality to its growing fleet of nuclear-powered ballistic missile submarines.

In any case, as India’s global ambitions grow, so does its nuclear deterrence program.