The US is currently operating at least two foreign fast jet types - MiG-29 and Su-27. They have been doing so for quite some time.
The assets are owned by the Air Force Flight Test Centre, AFMC, and have been thoroughly exploited by the Red Hats. Ongoing tactical exploitation - and exposure for guys going through the Weapons School and Aggressor programmes - is conducted by Det 3, 53d Wing. The RAF has a pretty good relationship with both of these FME (foreign military exploitation) units...
It's amusing that the mainstream media are making such a big deal out of this, but hardly surprising.