Some analysts believe this most recent demonstration of nuclear power by North Korea, allowing for an American scientist to visit and report back his observations, is an effort by Kim Jung Il to ready his son, Kim Jung Un, to take over as leader of the country. Here is a timeline that shows North Korea's nuclear progression under Kim Jung Il's reign:
March 1993: North Korea says it will quit Nuclear Nonproliferation Treaty
June 1994: North Korea announces withdrawal from the International Atomic Energy Agency
July 2000: North Korea threatens to restart nuclear program if U.S. doesn't compensate for electricity losses from delay in building nuclear power plants.
October 2002: Reportedly, North Korea tells visiting U.S. delegation it has 2nd covert nuclear weapons program
December 2002: North Korea expelled monitors from the International Atomic Energy Agency
January 2003: North Korea declared its withdrawal from the international Non-Proliferation Treaty
October 2003: North Korea announced completion of reprocessing spent nuclear fuel rods (to extract weapons-grade plutonium) and was developing a "nuclear deterrent"
February 2005: North Korea announces it has nuclear weapons
October 2006: North Korea says it has conducted its first-ever nuclear test
May 2009: North Korea conducts underground nuclear test
November 2010: An American scientist reports the existence of a new nuclear facility and North Korean claims of 2,000 operational centrifuges