this -- an historic phone call between president and raul castro. >> the soviet military build-up on the island of cuba. >> the first level of engagement, the white house says, sints cuban revolution more than 50 years ago. >> we will end an outdated approach that for decades has fail odd advance our interests and instead we'll begin to normalize relations between our to two countries. >> the secret talks started in 2013, with most of the discussions happening in canada and led by ben rhodes. those wheels were in motion when the president and raul castro shook hands at nelson mandela's memorial service last december. but one key sticking point remained -- the imprisonment of alan gross in cuba. >> a major obstacle stood in our way. the wrongful imprisonment in cuba of a u.s. citizen and u.s. a.i.d. subcontractor alan gross for dpooif years. >> last march, president obama found a pivotal player to help