Tu-4 Bisons.
Bisons are not supersonic.
But it appears it is a false report anyway. (Posted 1 hour ago.):
http://finance.yahoo.com/news/russia-denies-talks-argentina-leasing-jets-102502136.html
Back in December, it was announced the SU-24 would be leased to Argentina. Numerous publications stated this. However, to date, no transfers have taken place. Reported transfers, that is.
Tu-4s were codenamed “Bull”, not Bison.
Rumor was that they got that name when someone said “Look, the Soviets have B-29s” and the immediate reply was “Bulls**t!”
It is not supersonic and only one is in museum.