The introduction of MIRVed missiles in Asia is likely to prompt a major nuclear arms race in the region.

of the country’s Agni-5 ship-launched ballistic missile (SLBM), fitted with multiple independently targetable re-entry vehicle (MIRV) technology, could ignite a regional nuclear arms race ...

Russia's Sarmat missile keeps having troubles, including apparent catastrophic failures, and there's nothing in the works to replace it.