You see those ISIS members on numerous videos specifically threatening to attack the US have no credibility.
They have neither the capacity nor the interest in attacking the US.
They have never demonstrated the ability to carry out such threats.
I wounder what ISIS is going to have to do to ever be taken seriously. It must be very frustrating for them to constantly been warning of attacks and carrying them out only to be referred to by our government as having 'no credibility' over and over again.
It ain’t over until it is over. AQ hit the WTC in 1993 and came back again in 2001 to finish the job. I suspect any major ISIS attack will be a spectacular one. Maybe they are waiting until Obama leaves office.