NEW DELHI, Feb. 19 -- India is set to strengthen its nuclear triad, or ability to launch strategic weapons from land, air and sea, as the navy prepares to induct a new locally-made nuclear-powered ballistic missile submarine, officials aware of the matter said on Wednesday.

The submarine, Aridaman, is expected to be commissioned into service in April, the officials said, asking not to be named. Aridaman will be the navy's third Arihant-class submarine, and will serve as an undetectable launch platform for missiles armed with nuclear warheads.

The fourth SSBN codenamed S-4* is likely to enter service in 2027, as previously reported by HT. SSBN stands for ship submersible ballistic nuclear or nuclear-powered ballistic missile submarines....