The concepts of 'attack' and 'defense' are based on the concept of 'destruction'.
Destruction based concepts operate on the assumption "he who can destroy a thing controls it", which is many times an invalid assumption.
Let's take a look at some weapons as examples for the concepts of 'attack' and 'defense': sword and shield, gun and bulletproof vest, nuclear bomb and nuclear bunker.
Tools of attack and defense are not often clearly delineated: you can parry with a sword, or you can bash with a shield. You can even hit someone on the head with a pistol.
As time progressed, weapons became more specialized; less diverse, more powerful and harder to defend against.
Thus, most time the actual weapon used was not the physical weapon, but the threat of using the physical weapon - from sword to gun to nuclear bomb, the threat (and immunity to threat) became powerful weapons themselves.
Thus, the concepts of 'attack' and 'defense' shift levels of abstraction.
The concepts of attack and defense are 'flat'; they can be used with success in only one 'plane' of thought.
As warfare progressed, to expand the concept of war with new ideas, the idea of multi-dimensional warfare was introduced: attack and defense in many directions.
Planar thinking has deficiencies.
When facing an enemy with a sword, a gun, or a nuclear bomb, we can use the 'in plane' defense - that of shield, bulletproof vest, or nuclear bunker.
However, if we don't think in terms of attack and defense, we could take the 'high approach' of controlling the enemy wielding the weapon, or the 'low approach' of using information to evade the weapon.
The concepts of 'attack' and 'defense' are simple, but also many times simplistic in the context of warfare.