I didn't mean a specific state, I just wanted to imply that terrorists backed by a state - with the money and connections that encompasses - would have the means to do this.

I currently don't see any state that would wish to cripple the internet. That would hurt indiscriminately.

Perhaps in the future, before a planned attack, to sow chaos. So China or Russia perhaps.

Perhaps North Korea, but I don't think they have the power or knowledge to do something like that and China would get mad.