Delegations from some 190 nations begin a review of the nuclear Non-Proliferation Treaty on May 2nd., amid growing nuclear concerns and mistrust in the world. North Korea, which withdrew from the treaty in 2003, claims to have built nuclear weapons and refuses to return to six-nation talks to resolve the crisis over its nuclear program. Iran said it may restart this week activities related to its controversial uranium enrichment program, which the United States says is a cover for nuclear weapons plans. Many nations, meanwhile, complain that the nuclear powers are moving too slowly toward scrapping their nuclear arsenals. The 35-year-old Non-Proliferation Treaty obliges 183 states to forswear nuclear arms in exchange for a pledge by five nuclear powers -- the United States, Russia, Britain, France and China -- to move toward nuclear disarmament. Treaty reviews take place every five years.