Just focus on 100 years ago, you would see that any two countries were engaged in a war to destroy each others, the war was mainly a military clash between that two. And who was the supreme compared to military power and had supreme war strategies, they beat others and controlled the losers. This was going a long time ago. May be this tendency started at the origin of the mankind when two sons of Adam (PBUH) engaged themselves in a clash and one killed others by his arms power.
But the strategy to be upholder on others has changed its technique. Military war strategy has not seen a long period though recently some wars broke out brutaly. But this war broke out only the situation goes to an extreme situation. Before the situation goes to extreme, most of the countries try to destroy the opponents economically and culturally. And this new strategy has already succeeded to a great extent.
When the economic condition of a country will destroy, they don't have enough rice, enough bread and enough food. They have to starve. And at this moment they will lose their physical and moral strength to fight against others.
Cultural invasion is more brutal than any others as I think. If you can destroy the mainstream culture of a group of people, then they will lose their identity. They will even forget what to do, how to do and when to do in their life. And at this moment a man is not more than a crystal of flesh and blood. They have no moral strength to live with full respect and dignity.
All things are changeable. War strategy is also so. This should be properly thought to be free, to stay free .............