Two top former military officials have asked the Union government to immediately approve the production of nuclear submarines to ensure a guaranteed second-strike capability for the Indian armed forces.

Noting that India had a declared 'No First Use' policy, former Navy Chief Admiral (Retd) Madhvendra Singh and former Army Chief Gen S Padmanabhan have, in separate articles in the forthcoming issue of Indian Defence Review, asked the government to make nuclear submarines available to the armed forces of the country.

"Strategic forces need to be built up to 'deterrent' levels against a major power like China. The nuclear arsenal must, therefore, be enlarged and diversified to include thermo-nuclear weapons. To ensure guaranteed second-strike capability, submarines capable of launching thermo-nuclear weapons must be available," Padmanabhan said.

The former Navy chief said, "The government should approve, start and fund such a programme at the earliest, as it is vital for the security of the country. The ultimate aim should be to have at least four such submarines so that at least one, if not two, are on patrol duty at all times."

According to Singh any country with a No First Use policy, must have an assured second-strike capability. "Missile silos, airfields and aircraft are easily detected by satellites and are hence easy targets. A nuclear submarine is very difficult to detect. Even if detected, it is extremely difficult to target, as it is constantly on the move at speeds of 20 knots or more," he said.