Why exactly are terrorist attacks Islamic and not Political?

Yes i agree most terrorists Yell Allah hu Akbar and religious things aloud and say they are fighting for God.However,i fail to understand how people don't see the politcal roots of all this? Most people seem to be clueless about the wars and suffering inflicted upon the palestinians by the americans and the israelis.If all this was religious why wouldn't Muslim terrorists attack countries like Sweden,Denmark,Japan,China(There are some problems but those are totally political) ,South Korea,Singapore,Thailand,Burma,Sri Lanka,most countries in europe except "Great Britian" and countries that actually have troops sent to afghanistan.After all ,most of the countries in asia are much easier targets then the US also,sweden /china/japan etc have alot of Atheists.Why would Muslims choose to attack the US but not much easier targets?