While the accusation that the United States is becoming increasingly isolated could be argued, it had nothing at all to do with this attack.
It is precisely our involvement in the Middle East which has caused this terrorist attack. The attack was most likely comitted by radical islamic groups that oppose any kind of peace in the region, so saying that increased US involvement would of helped is completely wrong.
And even though it was our international involvement which caused this attack, I do not support ending our involvement, because that would be giving into the terrorists.