According to a North Korean defector, work on the Taepo Dong-2 began in 1987, with then-leader Kim Jong Il saying to researchers, "If we can develop this we have nothing to fear. Even the American bastards won't be able to bother us."
Estimates of the missile's range vary, and it has never been test-fired. In a December 2001 report, the CIA estimated a 10,000 km (6,200 mile) range for the two-stage version, enough to hit Alaska or Hawaii, and 15,000 km (9,300 miles), enough to hit any point in North America, for a three-stage version.
Sources: Federation of American Scientists, CIA