Well if we are perfectly pedantic this isnt a question we can really answer with the 20 year rule. And that is because there are international military units stationed in the US to this day. Cohabitants on and sharing bases just as the US does in many host nations, and like the US often with forces stationed there with a focus on training and developing familiarity with the host nation.

A perfect example is the German Air Force. All their flight training is done in the US, in part because of their history as a rebuilt force and in part because there is lots of open space to train, and to improve interoperability with an ally. Holloman Air Force Base in New Mexico hosts the majority of their infrastructure for this, though it was previously spread across many bases, including with the Navy at Pensacola.

There is also the 80th Training Wing at Shepard Air Force Base in Texas, which is actually a specially formed NATO-EU joint unit. So it has trainee pilots from the US, and EU-NATO allies like Belgium, The Netherlands, Spain, Italy, etc, under an internationally manned command and instruction structure. All to improve standards across the larger allied forces, and familiarity with operating with groups who all do things just a bit different.