MOSCOW — After months of prelude, Russian and American teams sat down in Moscow on Tuesday to begin renegotiating the 1991 Strategic Arms Reduction Treaty, or Start, a key plank in the promised “reset” of relations between the countries... Separately, a report released Tuesday by the EastWest Institute, a New York-based policy organization, concluded that a European missile defense system — a bone of contention between Russia and the United States — would not protect against a nuclear threat from Iran. The group recommended canceling plans to station radar facilities and interceptor missiles in Poland and the Czech Republic, deployments the Kremlin sees as a threat...