THE MOSCOW TIMESNorth Korea has had nuclear-weapons-making capability for four years, the daily Izvestia reported Friday. It printed a KGB memo from February 1990 signed by its head, Vladimir Kryuchkov, saying, "from information we have received, development of a first atomic nuclear device has been completed in North Korea's nuclear research center in Yongbyon in the province of Pyenanpunkto."But the document goes on to say that North Korea, then an ally of the Soviet Union, had no plans to test a nuclear device "in the interests of concealment from the world community."The document adds another piece to the confused mosaic of information about North Korea's nuclear capacity at a time when the United States and the International Atomic Energy Agency have registered alarm about Pyongyang's nuclear-weapons intentions. The CIA has estimated North Korea has already built one or two nuclear bombs. The scientist who supervised construction of the Yongbyon research center, Vladislav Kotlov, appeared to confirm the Izvestia report when he said earlier this week that North Korea had the "possibility" of constructing nuclear weapons, although he had no evidence that the country had actually done so.But Foreign Minister Andrei Kozyrev told Izvestia in an interview last Saturday that "experts consider Pyongyang needs three to seven years" to build a nuclear bomb.