Tensions are on the rise between the U.S. and North Korea, after the Communist country admitted it has been actively pursuing a nuclear weapons program.

The standoff between Washington and North Korea began in October 2002 when the North Korean government admitted publicly that it had been secretly developing a nuclear weapons program, a move that conflicted with a 1994 agreement to end all nuclear programs.

The declaration came after the U.S. said it had evidence North Korea was enriching uranium, a process that creates a more radioactive form of the mineral. According to State Department spokesman Richard Boucher, "the only purpose for doing that is to develop nuclear weapons." (For additional information about the nuclear weapons production cycle, click here.)

The 1994 agreement

Over the past decade, North Korea's strict government-controlled economy has failed to produce enough food to feed its people. Americans officials have long worried that to ease its economic difficulties North Korea would sell weapons to countries or groups hostile to the United States.

In 1994, the Clinton administration convinced North Korea to stop its nuclear weapons program and allow United Nations monitors into the country. In return, the U.S. and other countries pledged to replace North Korea's nuclear power plants that produce plutonium, a key ingredient in nuclear weapons, with light-water reactors, which don't. They also agreed to send North Korea oil to help replace the electricity lost when the nuclear plants shut down.

Both sides also agreed to lift trade barriers and pursue diplomatic and economic relations, including economic aid to North Korea.

However, North Korea's admission that it had not completely ended its nuclear program angered the U.S. enough to stop the fuel oil shipments. North Korea countered that the U.S. did not fulfill its promises from the 1994 agreement, including the construction of the power plants. U.S. officials say this will not happen until North Korea allows greater nuclear weapons inspections throughout the country.

U.S. - North Korean relations

Relations between North Korea and the U.S. have been rocky since the end of World War II. When Japan surrendered in 1945, it gave up its claim to the Korean peninsula, which it had occupied for fifty years. At that time, the allies drew a line at the 38th parallel -- the 38th degree of latitude on the map -- dividing Korea into northern and southern regions.

The Soviet Union occupied the North and the U.S. occupied the South. The goal was to eventually unify Korea, but the Cold War made the division permanent as of 1948. On June 25, 1950 North Korea attacked South Korea and the Korean War began. Eventually an armistice - a temporary cease fire agreement -- was signed in 1953, ending the fighting.

The two sides have never agreed on a political solution. Korea remains divided at the 38th parallel, known as the Demilitarized Zone (DMZ). The DMZ is one of the most heavily armed borders in the world. North Korea remains a Communist nation, controlled by leader Kim Jong Il. South Korea is a Democracy led by recently elected Roh Moo-hyun.

North Korea's nuclear program

The International Atomic Energy Agency (IAEA)-- a group that monitors nuclear facilities for the United Nations -- says North Korea has now moved fresh fuel to a nuclear reactor.

North Korea already removed monitoring seals and cameras at the Yongbyong complex, 55 miles north of the capital, Pyongyang. And in December, North Korea expelled the U.N. inspectors.

The government in Pyongyang claims that the reactor will be used to provide electricity that it desperately needs, but the U.S. State Department officials say this reactor has never produced electricity in the past. Also, experts agree that North Korea would not have to remove the seals and cameras if they only intended to produce electricity.

U.S. - North Korea Diplomacy

Speaking to reporters last week, President Bush said he believed there would be a peaceful resolution to the Korea conflict, saying "it's a diplomatic issue, not a military issue, and we're working all fronts."

North Korea has said it wants the Bush administration to revalidate agreements made in the fall of 2000 with President Clinton, including a U.S. pledge to not use nuclear weapons against them. In addition, North Korea would like the U.S. to normalize relations. The U.S. claims that the North has stalled this process.

The IAEA has not yet filed a report with the U.N. Security Council, a move that could lead to sanctions against North Korea. Instead IAEA chief Mohamed ElBaradei asked North Korea to adhere to past agreements and allow the return of weapons inspectors.

-- By Annie Schleicher, NewsHour Extra