Extradition treaty with Bulgaria and an agreement on certain aspects of mutual legal assistance in criminal matters with Bulgaria : message from the President of the United States transmitting Extradition Treaty Between the Government of the United States of America and the Government of the Republic of Bulgaria (the "Extradition Treaty" or the "Treaty") and the Agreement on Certain Aspects of Mutual Legal Assistance in Criminal Matters Between the Government of the United States of America and the Government of the Republic of Bulgaria (the "MLA Agreement"), both signed at Sofia on September 19, 2007.