I'm always skeptical of these "nation state" claims, it seems like an easy way out of any tough question about the security of these systems. "No, no, you don't understand, it's not that our systems are insecure, it's that the attackers where highly sophisticated and had the resources of a nation state, otherwise it would never have worked out". I suppose "we think it could be done by a group of two or three teenager…
Also, the attack was carefully crafted. How could anyone expect or defend against a carefully crafted attack, by a nation state no less.