Prime minister Narendra Modi says the first successful voyage by India’s home-built nuclear submarine is a ‘warning for the country's enemies’. The INS Arihant recently completed a month-long ‘deterrence patrol’, meaning India now has the capability to fire nuclear weapons from land, air and sea. Mr Modi, a Hindu nationalist, tweeted it was a ‘fitting response to those who indulge in nuclear blackmail’. In a speech televised nationwide, he told the submarine’s crew, ‘Amid an increase in the number of nuclear weapons in our surroundings, a credible nuclear deterrence is extremely important for our country's security’. His words are a thinly-veiled reference to India's neighbours, China to its north and its traditional enemy, Pakistan, to the west. The often volatile relationship with Pakistan has cooled even more noticeably since Mr Modi took office in 2017 and adopted a more assertive strategy towards its arch-rival.