YEREVAN, MAY 19, ARMENPRESS. The key to a peaceful, democratic, and prosperous future in the South Caucasus region is a negotiated, comprehensive, and sustainable settlement of all remaining issues related to or resulting from the Nagorno-Karabakh conflict, Ambassador of the United States of America to Armenia Lynne Tracy said in an exclusive interview to ARMENPRESS, which was conducted on April 29 on the occasion of the 30th anniversary of the establishment of Armenia-US diplomatic relations.