During the mid- and late-1980s, North Korea sought to insulate itself from the reform movement in the Soviet Union called perestroika, or what Kim Il Sung considered "the most dangerous and destructive form of modern [socialist] revisionism in the form of Gorbachevism."

Speaking before the Supreme People's Assembly in Dec. 1986, Comrade Kim Il Sung, who called himself "the Great Leader of the Korean Revolution," said:

"The people's government must guard against the poisonous ideas of capitalism and revisionism and resolutely fight against all attempts to infringe upon the socialist system."

In 1984, North Korea test-launched the Scud-B, a missile it had reverse-engineered using various defense materials. By 1987, North Korea had developed its missile industry to such an extent that it was able to supply Iran with weaponry during the Iran-Iraq war (1980-1988).

North Korea further developed its nuclear infrastructure between the mid- to late-1980s, including building a graphite-moderated reactor that sidesteps foreign involvement and constraints, according to U.S. sources. North Korea has never officially acknowledged this reactor's existence.

In the late 1980s, U.S. satellites detected the construction of a nuclear-related research site -- including a second reactor and affiliated support facilities -- near the Yongbyon facility. According to U.S. congressional documents, the facilities, once completed, would give North Korea the complete nuclear fuel cycle needed for weapons production.

In 1985, North Korea became one of 180 countries to sign the Nuclear Nonproliferation Treaty, but delayed signing the corollary IAEA Full Scope Safeguards Agreement until 1992. In signing the safeguards treaty in 1992, Pyongyang agreed to allow inspectors to monitor all of its nuclear and research facilities.

In 1989, North Korea first test-launched its long-range Scud-C missile, which the United States believed was developed in the mid-1980s.

-- Compiled by Liz Harper for the Online NewsHour