The American position centred on the belief that supplying Western military equipment was essential because the preceding Argentine administration had been “flirting with China and Russia”.

Two additional sources, comprising one British official and one Argentine representative, verified that these conversations occurred and confirmed American pressure had been applied.

Britain’s longstanding policy bars the export of any weapons or components to Buenos Aires, a restriction implemented due to the competing claims over the Falkland Islands that led to the 1982 conflict.

Reports emerged on Friday that the Pentagon has assembled a catalogue of potential retaliatory measures against Nato allies considered insufficiently supportive of the American and Israeli campaign against Iran.