Any time you give a weapon to somebody, there is at least one of these two things happening if not both;

You are sure this person is your friend and ally and is therefore no threat to you;

You have a better weapon/the full capability to defend against the shared weapon without fear upon sharing it, thus ensuring your superiority in any potential engagement with what was formerly yours.

In this case, both of these were/are true. Quite simply, the US fleet will remain functional in greater numbers for longer even if it is no longer a reliable ally of global freedom, and the pilots have had far more experience in the cockpit of fully functional vehicles to boot. So even in an engagement where the technology is a literal 1:1 match, pilot skill and experience will absolutely make the difference and the US military knows that.

Anyone else remember Star Wars 1313? Same concept except done by Lucas arts; you were going to play a Republic pilot(?) who ended up investigating the Coruscant Underbelly, the parts of the planet so close to the actual ground that natural light hasn’t been seen for over a thousand years.