FISA and the Stored Communications Act as modified by the CLOUD Act don't distinguish between (i) parent company overseas + US subsidiary and (ii) parent company in US + foreign subsidiary. In both instances the US asserts personal jurisdiction, extending to wherever the data is stored geographically.
The US by and large can (and does) assert authority outside of its jurisdiction, from which another country can choose to capitulate.
Most of the time countries do, because they are all swapping data on their citizens between themselves to skirt various laws.
In the case where the US really wants something, and the country won't yield, they'll fund contras or destabilize the government (if small enough to be bullied) or impose sanctions so drastic it's effectively a soft act of war.
This is all to say that, the US has nearly unlimited authority while it stands as the world's defacto superpower.
If the violent, untrustworthy, Americans choose to go to war with their former allies over some data then that's their choice. Better than just giving these warmongers everything they want.
