[mani]

Though the ship was outside of the 200-mile (320 km) exclusion zone, both sides understood that this was no longer the limit of British action — on 23 April a message was passed via the Swiss Embassy in Buenos Aires to the Argentine government, it read:

In announcing the establishment of a Maritime Exclusion Zone around the Falkland Islands, Her Majesty's Government made it clear that this measure was without prejudice to the right of the United Kingdom to take whatever additional measures may be needed in the exercise of its right of self-defence under Article 51 of the United Nations Charter. In this connection Her Majesty's Government now wishes to make clear that any approach on the part of Argentine warships, including submarines, naval auxiliaries or military aircraft, which could amount to a threat to interfere with the mission of British Forces in the South Atlantic will encounter the appropriate response. All Argentine aircraft, including civil aircraft engaged in surveillance of these British forces, will be regarded as hostile and are liable to be dealt with accordingly.

Interviews conducted by Martin Middlebrook for his book, The Fight For The Malvinas, indicated that Argentine Naval officers understood the intent of the message was to indicate that any ships operating near the exclusion zone could be attacked. Argentine Rear-Admiral Allara who was in charge of the task force that the Belgrano was part of said, "After that message of 23 April, the entire South Atlantic was an operational theatre for both sides. We, as professionals, said it was just too bad that we lost the Belgrano".