Respuesta :
If the aggressor were not stopped, they would definitely conquer and take down nations as they could. For an example, Adolf Hitler was one of the most famous aggressors during the World War II. He started conquering the European countries which alarmed Churchill to put an end to it.
If the aggressors were not stopped, they would soon to conquer their target area and spread their political power and influence upon it.
This would make the aggressors nations able to obtain the resources of the defeated, which make their military power become even stronger. So they need to be stopped as soon as possible before they become too troublesome too deal with.