Navy Day in India is celebrated on 4 December every year to recognize the achievements and role of the Indian Navy to the country. 4 December was chosen as on that day in 1971, during Operation Trident, the Indian Navy sank four Pakistani vessels including PNS Khaibar, killing hundreds of Pakistani Navy personnel. On this day, those killed in the Indo-Pakistan War of 1971 are also remembered.
Navy Day in India is now celebrated to commemorate Operation Trident, which was the attack on the Karachi harbor during the Indo-Pakistan war (on 4 December 1971) by the Indian Naval Missile boats as well in to reverence all the martyrs of that war. During the attack, Indian sailors communicated in Russian to avoid detection. No Indian sailors were killed in the attack.