I have visited Costa Rica and it was one of the best trips ever. I truly loved the country and you mention many wonderful aspects of being there.

As far as not having an army, according to The Costa Rica Daily, The US donates armored trucks to the National Police and has financed surveillance planes.

If Costa Rica were to be attacked, it would invoke the Inter-American Treaty of Reciprocal Assistance, which obligates regional powers — including the United States — to assist.