Some of the items required are made in Europe, as is the case for the AS2000 auto injector, made in Italy. Since these are parts of an isotope ratio mass spectrometer of United States manufacture, they cannot be obtained by Cuba.

But those ways of being rational are not independent of one another, so it's rational for a drug injector to share needles because of a stupid decision that's made by a politician, and it's rational for a politician to make that stupid decision because they're responding to what they think the voters want.