1: Cuba has historically been the wrench in the diplomatic machinery , with some Latin American leaders threatening not to attend the Summit of the Americas if the United States and Canada did n't agree to invite President Raul Castro . 2: Later , Obama issued an executive order sanctioning seven Venezuelan officials for human rights violations and saying the country was a  threat to national security .  3: U.S. , Venezuelan relations threaten to overshadow Obama , Castro meeting .
1: Latin American 2: Venezuelan 3: Venezuelan