Why was the sinking of the General Belgrano controversial?

The sinking of the Argentine cruiser General Belgrano on May 2, 1982, by a British nuclear-powered submarine remains controversial primarily because the vessel was attacked while located outside the 200-mile war zone that the British government had previously declared around the Falkland Islands.1

The event resulted in a significant loss of life, accounting for approximately half of the total 650 Argentine casualties during the conflict. Following the sinking, the Argentine navy largely withdrew its ships to port, limiting its remaining contributions to its naval air force and a single diesel-electric submarine.12