Iran has a security pact with Serbia.
The US needs Croatia over an agreement between Iran and Serbia
http://www.nacional.hr/en/articles/view/29168/
Please provide links, documentation or any verifiable evidence.
I find it highly unusual (and unlikely) that a fundamentalist Islamic government would engage in a security agreement with an Orthodox Christian nation that has a long history as being an enemy of Islam and is currently in a dispute with one Muslim 'state' (Kosovo) and was recently at war with another(Bosnia).