Why would calling MEZ a blockade create problems under international law?

As British forces drew closer to the South Atlantic the potential scope and intensity of hostilities grew. In the weeks before the bulk of the task force arrived, all the British could do was inhibit Argentine reinforcements. This was the purpose of the Maritime Exclusion Zone (MEZ) announced on 7 April to take effect from 12 April. The military would have been content to call it a blockade, but this created problems under international law, and so the more neutral terminology was adopted. (Signals of War, p.248)

Can anyone enlighten me why calling MEZ a blockade would create problems under international law?

A blockade is restricting navigation to and from another sovereign nation and is considered an act of war upon that nation. Calling a British restriction around a British territory a blockade would be an admission that that territory actually belonged to someone else (ie Argentina).

Thank you, Elmer_J. Fudd.
So calling the blockade MEZ was a contingency plan for fear of being mistaken that the UK admitted the Falklands belong to Argentina under international law. Correct?

In the case of the US’s naval ring that was designed to stop potential Soviet replenishment of military supplies of Cuba during the Cuban missile crisis, they needed to declare it in advance, as stopping ships without warning was either war or piracy, but then they needed to find a word that means blockade without saying blockade. The term they chose was ‘quarantine’.

I’m not sure whether they needed to nominate an infectious disease or provide some alleged non-military issue that the quarantine responded to, but it seems an overly easy and legalistic way to circumvent an element of international law. Maybe everyone was just relieved that the US, and subsequently the Brits, deliberately chose to peg their actions at one level below ‘Blockade = Declaration of War’.

Thank you, Banksiaman. This sounds like a game of wording, but I think it is just the way it is.

There’s also the possibly hair-splitting difference between a “blockade” which prohibits all traffic of whatever nation and whatever nature from reaching the blockaded area, versus an “exclusion zone” which meant, in this case, no Argentine warships or military auxiliaries allowed. Big difference.

Lincoln also had this problem. He wanted to blockade Conferderate ports but was told you only blockade other sovereign nations, so instead his order closed the ports.