From the Merriam-Webster Online Dictionary:
a : the act or action of
defending <the
defense of our country> <speak out in
defense of justice>
From the Oxford online dictionary:
- 1the action of defending from or resisting attack:they relied on missiles for the country’s defense she came to the defense of the eccentric professor
- attempted justification or vindication of something:he spoke in defense of a disciplined approach
- an instance of defending a title or seat in a contest or election:his first title defense against Jones
- military measures or resources for protecting a country:the minister of defense [as modifier]:defense policy
- a means of protecting something from attack:education is the best defense against tyranny
- (defenses) fortifications or barriers against attack:
Nothing there that indicates limited as a definition of defense. Is that what you are hanging your hat on? Even if so, our current conflict in Afganistan is hardy all out war. It is limited in geography and weapon use. Also there is nothing in the above definitions to indicate life and property, but I would agree there is a strong aspect of that for the person/country initiating a defense. Then you can ask how the actions one claims are defense does that.
If there is a threat to a country or its citizens, then I think you can make some actions taken by the country to protect them, fit into a definition of defense. The real problem in my opinion, is how far you are willing to reach out. Do you wait until domestic territory is attacked? Do you wait until an ememy is 50 miles away on an attack course, 100 miles? Would you take action against an enemy at some point before the enemy attacked your territory, knowing the countries intent was to eventually attack, even if there wasn't an imminent attack?
I think we decided after Pearl Harbor that we didn't want to wait for attacks if we could stop them before they occurred. We intervened in Korea. We intervened in Vietnam, and more recently in Iraq and Afganistan. I think the reasonn is that after WWII, the world was effectively divided between the US and Russia, and their allies, with other countries more or less neutral. It seems to be the case that our country decided that anything that made Russia and her allies gain more territory, had to be stopped. Understand that territory brought manpower and natural resources directly, as conquered territories, and indirectly as other countries decided to cooperate with the other side, out of fear.