RARELY does nemesis follow hubris so quickly. On August 10th India’s prime minister, Manmohan Singh, proudly announced that the reactor of the country’s first indigenously designed and built nuclear-powered submarine, the Arihant (“Destroyer of Enemies”), had been activated and the vessel would soon begin sea trials. This “giant stride” was quickly followed by another, two days later, with the launch of the country’s first domestically built aircraft-carrier, the Vikrant, which is expected to enter service in 2018. But in the small hours of August 14th an explosion on board an Indian navy submarine berthed in Mumbai killed 18 sailors. The vivid explosion that lit up the city swiftly eclipsed the earlier, patriotic glow, bringing to a premature halt all the celebrations the admirals had intended.

The cause of the explosion on the 16-year-old Sindhurakshak, built in Russia, is not yet known for certain. But it is likely to be the result of hydrogen gas leaking during the recharging of the batteries that propel the Kilo-class submarine when it is submerged. A fire seems to have spread to the missile compartment: the Sindhurakshak carries Russian Klub-S cruise missiles, which have a range of about 200 kilometres (125 miles). That triggered a series of explosions that resulted in the submarine sinking and, according to some reports, the launch of two torpedoes that struck other vessels (including another submarine) in the dockyard. Internal bulkheads were destroyed by the force of the explosions, trapping or drowning the crew.

The Sindhurakshak had been reintroduced to service only in April after a refit in Russia, but it also suffered a battery-related fire in 2010 that killed a sailor. With nine other Kilo-class boats in the 14-strong submarine fleet, navy investigators will need to find out quickly whether the accident was caused by faulty manufacturing or by sloppy operation. The temptation will be to blame Russian quality control (with some reason). However, the Indian navy has a poor accident record, with several mishaps in recent years. In 2008 another Kilo-class boat collided with a merchant ship when it was exercising off Mumbai, and in 2011 a frigate, the Vindhyagiri, capsized after yet another collision at sea near Mumbai.

Ajai Shukla, the defence correspondent of India’s Business Standard, reckons that, after the accident, India may have only six submarines available for blockading shipping lanes in the event of a crisis—a key aspect of its naval strategy. He says that while the increase in India’s surface fleet, of which the Vikrant is the latest example, has been going well, submarines are lagging behind. Six French-designed but Indian-built Scorpène-class submarines are still at least three years from deployment, according to Mr Shukla. The Arihant is not an attack submarine, but one designed to carry ballistic missiles to complete India’s “triad” of land, air and sea platforms for its nuclear deterrent.

Yet despite this week’s embarrassing tragedy, it is the symbolic importance of the Arihant and the Vikrant that will live on. India’s navy is generally far behind China’s in overall size and capability, but it is actually ahead when it comes to operating carriers. Its ambition to be a serious blue-water force still burns brightly.