I don't know that much about the Lend Lease of our weapons, but the CMP has no control, nor input. They only do what is called for in their Charter.
I was told, that if the CMP ran out of guns today, they would be able to keep funding their programs almost indefinitely without tax dollars.
As far as selling, giving, returning, that's a State Dept issue and based on how grateful the other country is. Greece and other European countries were, S. Korea isn't.
Way above my pay grade.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071