Generally insurers won't provide cover for war and/or terrorism, however if at the time of booking or purchasing insurance there are no restrictions against travelling to the particular country and then an incident occurs which results in the FCO declaring the destination as a no go zone, travel insurers will usually pay out provided by the policy. However, if travel is booked after any incident then this is at the travellers own risk.

But please confirm with the insurer before taking the policy.