A top U.S. envoy said on Saturday he was pleased that Russia, like other members of the U.N. Security Council, believed Iraq posed a "challenge" that had to be resolved. U.S. Undersecretary of State Marc Grossman, speaking after talks with senior Russian officials, made no reference to a U.S.-drafted resolution setting down demands for Iraq to meet on what Washington says are weapons of mass destruction. "I think it is fair to say everybody agreed there was a challenge to the United Nations, to the Security Council, and that all of us who are permanent members...want to see if we...