The United States and Europe's top powers on March 8 expressed alarm at Iran having produced a small amount of uranium enriched to 84 percent purity -- close to weapons grade -- and said Iran must explain how it happened. The UN nuclear watchdog found uranium particles enriched to up to 83.7 percent at Fordow, a site dug into a mountain and the second place where it is continuously enriching uranium to up to 60 percent. Weapons grade is around 90 percent. The so-called spike is large, but it remains unclear whether it was accidental. To read the original story by Reuters, click here.