IMO, that would depend on when he happened to be the last time she saw her. If he was in her country, then they met outside the USA. If he was in the USA, then they met in the USA.
As you se, context matters. Please provide more context next time. It'll make things easier for all of us.
If you have a question about the English language and would like to ask one of our many English teachers and language experts, please click the button below to let us know: