In sport, such as football, the meaning of he word is clear. It opposes the other team,'s offense.
When it comes to politics, George Orwell would have appreciated the distortion of the word's meaning. We have a Defense department, successor to the former War Department. In the UK, although the word is spelled "defence", it is the same concept: it refers to all the armed forces.
The Israeli force that has destroyed much of Gaza's infrastructure is the IDF, the Israeli Defense Force. Lately, a more appropriate name might reflect its role in aggressive actions against Palestinians.