Hang international law. Only Congress has the authority to make war and they have abdicated this to the president since ww2. There's a reason why the constitution wants congress to have this power and not the pres. It's too easy for one person to want to use this enormous power to fix some perceived problem in a quick and overwhelming way. Cooler heads may prevail over a murky decision in a large legislative body and a real need (for war) would be obvious.
