That 5% figure is arbitrary though. If the threat is a real one, and the intention is carry out a terrorist attack, you could assume that it will happen because

That 5% figure is arbitrary though. If the threat is a real one, and the intention is carry out a terrorist attack, you could assume that it will happen because the people behind it mean business. If it is bluff, then there is no risk at all. Certainly I agree risks like this are not worth worrying about, life is full of risks.