South Korean officials pressured the US for years to revise an agreement limiting the range of their missiles before the US finally agreed. Under terms of the 2001 agreement, South Korean missiles could reach targets no farther away than 300 kilometers (186 miles).
As for North Korea, it has an assortment of short- and medium-range missiles and has tested a long-range Taepodong missile in August 1998 with a theoretical range as far as the US West Coast. That missile flew over Japan, landing in the western Pacific south of Vladivostok, Russia. North Korea has also twice tested long-range Taepodong missiles that plummeted into the sea shortly after takeoff – most recently two days before the massive celebration on April 15 marking the centennial of the birth of "Great Leader" Kim Il-sung, grandfather of the North's current leader, Kim Jong-un.
North Korea is assumed to be developing the capacity to attach warheads to missiles but is believed to be far from achieving that goal.
A sense of rising confrontation with North Korea, however, has added urgency to the whole issue of South Korean missile development. South Korean President Lee Myung-bak ordered defense officials to produce long-range missiles as quickly as possible at a cost of more than $2 billion. South Korea is expected to be able to deploy new model missiles within five years under terms of what South Korean officials call a “landmark” deal with the US.