War has historically been against a nation-state, or possibly a land mass or ethnicity. And there is clear endgame: surrender by recognized leaders, or unequivocal military domination. But terrorist cells have no leaders, and cannot surrender en masse. And the only way to dominate them militarily is to dominate the entire globe.
The "War on Terror" is not a war. It is declaration of ownership, that says we can deploy military might whenever and wherever we want.