The paradox of engaging in 'humanitarian war' against pre-modern opponents is that it requires a disproportionate level of force to achieve peace and respect. The belief that everyone loves their children the same and desires the same world has led to the misconception that war can be clean and antiseptic, making it easier to enter but difficult to win. To win a war, one must use overwhelming force to destroy the enemy's capability to make war and impose terms for peace. This approach was exemplified by the surrender of Japan after the US used a massive level of force, leading to peace and respect. The speaker highlights that despite the belief in human nature evolving, adversaries remain unchanged, especially those who are pre-modern. The speaker also emphasizes the importance of maintaining a targeted approach in warfare to avoid incentivizing adversaries to use tactics like exploiting their own children to pressure their enemies.