Selling a war to an unsuspecting public.
The seller, often a chickenhawk could be anyone with influence, such as an elected official or a talk radio blowhard, who paints the best possible picture of war, ignores the negative aspects of war, and warns of dire consequences of not going to war. Often war mongering hides behind patriotism and the loyalty of troops to deflect criticism.
By mentioning mushroom clouds, Shrub was war mongering, selling Americans a war by using fear tactics.
The war mongering Rush Limpbag said anyone against going to war was not supporting the troops.