>It depends on the scale of threat and the potential efficacy of military
action. >When the threat is large (i.e. there's good reason to think many
thousands will die >in the future as a consequence) and when it also appears
that military force will >diminish that threat to a large degree, then it's
justified. The question of whether >or not the threat is posed by a
government or a terrorist collective is not relevant.
There is also a scenario of state sponsored terrorism. And if the state sponsoring it is a nuclear weapon state, it is even worse. I was mainly writing about the use of covert and deniable (therefore, not verifiable in every case) acts of terror on the territory of thecountry A, by the state apparatus of the country B as an instrument of foreign policy.
War is one of the options. There could be other options or a combination of options. e.g. A could retaliate by resorting to covert and deniable acts on the territory of B.
Ulhas