You are half-right, in that any money spent goes somewhere, thus the government deficit spending to finance the war becomes business or household income. Howev

You are half-right, in that any money spent goes somewhere, thus the government deficit spending to finance the war becomes business or household income. However, war is expensive in strictly economic term due to the physical destruction of resources. A bombed factory cannot produce cars. If the skilled engineers needed to rebuild or operate the factor are not available (dead, otherwise occupied, etc), this will also result in economic loss. The investment to convert a factory from car-making to military-vehicle making only generates long-term value if the military continues to order from that factory. Otherwise, that investment does not generate a return, likewise it takes additional investment to convert it back to car manufacture. Ukraine is not selling much wheat this year, due to the war. Since this wheat is perishable, its economic value is lost.