SEOUL, South Korea -- Tensions over North Korea's nuclear programs intensified when the communist government expelled U.N. inspectors amid rising concerns the North was resuming nuclear weapons work.
Here are some questions and answers about the roles of North Korea and the United States in the Korean Peninsula:
Q. Why are U.S. troops in South Korea?
A. The United States keeps 37,000 military personnel in South Korea under a mutual defense treaty. The U.S. presence dates to the 1950-1953 Korean War.
The war ended in an armistice, not a peace treaty. U.S. troops have remained in South Korea to serve as a deterrent against North Korea across the world's most heavily armed border.
Q. Why is North Korea urging South Korea to stand with it against the United States?
A. It is North Korea's long-standing strategy to drive a wedge between South Korea and its chief ally, the United States. North Korea often calls South Korea a colony of the United States and urges South Koreans to rise against "U.S. imperialists." South Korea dismisses that as communist propaganda.
North Korea claims Washington keeps U.S. troops in South Korea to prepare for a northward invasion. Both Washington and Seoul say U.S. troops are meant to deter a North Korean attack.
Q. Why is North Korea making nuclear weapons?
A. North Korea has never publicly said it is, although it has said it has the right to develop atomic weapons. According to U.S. diplomats, North Korean officials told them the North has a nuclear weapons program using enriched uranium.
Experts believe North Korea is developing nuclear weapons as a deterrent against what they consider U.S. military threats.
Q. What are the prospects for defusing tensions?
A. North Korea claims the United States is plotting a pre-emptive nuclear attack on it. It says it will resolve international concern over its nuclear programs only if Washington promises a nonaggression treaty.
Washington says it cannot reward North Korea for flouting international agreements. It says it cannot trust North Korea and will open dialogue only after it abandons nuclear weapons programs.
Q. How serious is North Korea's security threat?
A. Besides nuclear weapons, North Korea also has a large arsenal of biological and chemical weapons, U.S. and South Korean officials say.
North Korea also is the world's most active exporter of missiles parts and technology to the Middle East, U.S. officials say. North Korea also alarmed the world by firing a test missile over Japan and into the Pacific in 1998. It is further believed to be developing missiles that could reach parts of North America.