War is big business for the military industrial complex. Its also employment for the unskilled population (read vote bank). Is this what drives countries to plan for for premptive wars? On one hand western block backs monarchs with a history of brutality and on the other hand war is declared on dictators who step out of line.
Below is a good article by Taj HAshmi of Clarksville, USA, highlighting the strong linkages between groups who benefit most from wars.