Correct me if I'm wrong, but don't you usually have only eight tiles to work with in Scrabble - or nine when linked to another word? So only countries with 8-9 letters or less should count.
It is possible to add to more than just one letter. For example "TAN" is a valid word on its own and this could easily be turned into "KAZAKHSTAN" with the addition of seven more letters from your rack.
Even "MOZAMBIQUE" could be created if words such as "AM" or "BI" were on the board.
Even "MOZAMBIQUE" could be created if words such as "AM" or "BI" were on the board.