Any aircraft of US manufacture (or aircraft that contains at least 25% US content) that is exported to another country, and which may contain certain technologies having national security implications. Also applies to such technologies themselves (chip designs, software code), whether aviation-related or not.
Among other things, that puts restrictions on
resale or other delivery of such an aircraft to a third country, unless approved by the US.
That limitation is (or should be) incorporated into the exporter's (i.e. Boeing's) sales contract, so that the
buyers know exactly what they are committing to.
Other economic sanctions of a punitive nature may also come into effect. Do business with a sanctioned country - and you are subject to the seizure of the proceeds or object of that business. Iran and Venezuela are
both currently under such sanctions, for one reason or another.
Under US law for aircraft as specified in paragraph one - that makes this 747 subject to seizure. Argentina seized the 747 at US request - and has now turned it over to US authorties, who had it flown back to the US.
BTW I am not arguing for or against the laws - simply stating that they exist, and are enforceable in US courts when/where possible.
Regarding the "25% content" caveat, see also:
https://www.reuters.com/business/aer...st-2022-08-02/