NEW DELHI: India's dissuasive nuclear deterrence against China got a tad more credibility on Tuesday with the country testing the Agni-IV ballistic missile , which has a strike range of 4,000km, from the Wheeler Island off Odisha coast in the morning.The Agni-IV was tested in "its full deliverable configuration" by the tri-service Strategic Forces Command (SFC) in the first such user-trials, after one failed and three successful "developmental trials" over the last four years.The actual operational induction of the missile, which was tested for a range of only 3,000km on Tuesday, will take another couple of years. DRDO scientists said there were no glitches during the missile's entire parabolic flight path, which was constantly monitored by long-range radars and electro-optical systems all along the coast, till its splash point in the Bay of Bengal.More fireworks are shortly expected over the Indian Ocean with the DRDO now gearing up for the third developmental test of the over 5,000-km Agni-V, the country's first true intercontinental ballistic missile (ICBM), in a month or so. The three-stage Agni-V is likely to be inducted by 2017.The SFC has already inducted the short and intermediate range Prithvi and Agni missiles geared towards Pakistan, which has overtaken India both in terms of missiles and nuclear warheads with covert help from China and North Korea over the years.The road-mobile Agni-IV and Agni-V, in turn, are specifically meant for deterrence against China, which can target any Indian city with its formidable inventory of missiles. Importantly, the Agni-V is now slated to be tested in its canister version, which will give the armed forces the operational flexibility to rapidly transport and fire it from anywhere they want, as reported earlier by TOI."With Prithvi and Agni-I, II, III missiles already in the arsenal, Agni-IV further extends the reach and enhances India's effective deterrence capability. Agni-IV is equipped with state-of-art avionics, 5th generation on-board computer and distributed architecture," said the DRDO.DRDO scientists are also progressing ahead with their work on "manoeuvering warheads or intelligent re-entry vehicles" to defeat enemy ballistic missile defence systems as well as MIRVs (multiple independently targetable re-entry vehicles) for the Agni series of missiles. A single missile with a MIRV payload can deliver multiple nuclear warheads to different targets.However, one worry that still remains is the lack of an operational submarine-launched ballistic missile (SLBM) to complete India's nuclear weapons triad. It will become a reality only after the indigenous nuclear-powered INS Arihant becomes fully operational. INS Arihant is slated to begin extensive sea trials, which will include test-firing of the K-15 (750-km) SLBM, in the near future, say officials.