ames-
Those are very good questions.
1) Did you think that the U.S. should disarm too? No. There are terrorist states that need to know we have the will and capability of nuclear retaliation if they strike us with WMDs (nuclear, chemical or biological).
2) Do you think Russia is really going to cut back on nuclear weapon stockpiles, like they just said they will do? That is mostly irrelevant, because they will definitely leave themselves enough to destroy the U.S. in case of war, as well as intimidate the neighborhood.
squeak-
One country that absolutely needs nukes is Israel. It is a serious deterrent to its surrounding enemies. They know that even if they defeat Israel militarily, Israel will use its nuclear arsenal if its survival is at stake.