Vladimir Putin warned the West Thursday that Russia has developed a high tech new arsenal — including a supersonic nuclear weapon that can reach any spot on Earth while avoiding missile-defense systems. Delivering his annual State of the Union address, the Russian president said his country was prepared to use its nukes if attacked, and added that Moscow would consider a nuclear attack on its allies as a nuclear attack on the Motherland — and would retaliate immediately. “I want to tell all those who have fueled the arms race over the last 15 years, sought to win unilateral advantages...