What leads to war

the question that i wanted to know is that through out history there has been many examples of religion leading to war…some examples might be islam there were war that were solely based on spreading religion…

but in the present day, present wars, are people fighting this war for political purposes or for religious purposes? wars suchs as indo/pak war, us/iraq war, us/afganistan war, isreal/palestine war…
are these wars religios wars or are there political war…(political war- wars that are fought based on politics like for land)