According to the British Jane's Defense Weekly on December 29, 2021, India's third "enemy Destroyer" class nuclear powered ballistic missile submarine code S4 was launched at the shipbuilding center in Visakhapatnam, India on November 23, 2021. Compared with the first two nuclear submarines whose launching ceremony once caused a sensation in India, the launching ceremony of this nuclear submarine with larger tonnage and stronger deterrence was extremely low-key and did not announce the name of the boat, so that the title reported by the British media was "India's third" enemy Destroyer "class nuclear submarine quietly launched". It is reported that after the submarine was launched, it was relocated to the area near the outfitting wharf to the north of the wharf, facing another submarine of this class. "India media has not yet reported the launch of the submarine, which may be delayed due to the delay in the service time of the second" enemy killer "class submarines due to COVID-19. “ From satellite images, S4 is much larger than the first two submarines of the series. According to the records in Jane's warship Yearbook, the total length of the first ship of this class of nuclear submarine "enemy Destroyer" is about 111.6 meters, with a displacement of about 6000 tons, while it is estimated that the total length of S4 is close to 131 meters, with a displacement of more than 7000 tons. It is speculated that the increased length of the submarine may be to accommodate the new vertical launch system - according to the information previously disclosed by Indian media, the number of vertical launch units of the submarine has doubled (8), and can carry 8 K-4 submarine launched ballistic missiles or 24 k-15 missiles. The range of the two missiles is 3500 km and 750 km respectively. It is worth noting that the K-4 submarine launched missile can be equipped with nuclear warheads, which also means that S4 will have considerable strategic strike capability. However, the US "wired" magazine website previously said that due to India's insufficient technical accumulation in submarines, the diameter of the 6000 ton "enemy Destroyer" nuclear submarine is the same as that of the 3000 ton Russian made "kilo" conventional submarine. Due to the too small hull diameter, the missile launching devices of the submarine can only be "lined up" and the space utilization rate is very low. In addition, since India is unable to provide qualified submarine steel, the "enemy Destroyer" class nuclear submarine uses steel imported from Russia, and its performance is only equivalent to the American hy80 special steel, which means that its maximum diving depth can only reach 300m, which is far from the current advanced submarines in various countries. (outlook new era)