Because you might disagree with it? How can you be so narrow-minded to not even fathom people having different fundamental beliefs? Why don't Israel and Palestine just merge into one country called Unicornia? Why don't all people just separate religious beliefs from government, or conversely, why don't we all just switch to the correct(tm) religion?
One country may not want to support terrorists while another wants to support them because they are 'freedom fighters', how do you propose they operate under the same foreign policy?