North Korea has been among the most vexing and persistent problems in U.S. foreign policy in the post-Cold War period. The United States has never had formal diplomatic relations with the Democratic People's Republic of Korea (the official name for North Korea). Negotiations over North Korea's nuclear weapons program have occupied the past three U.S. administrations, even as some analysts anticipated a collapse of the isolated authoritarian regime. North Korea has been the recipient of well over $1 billion in U.S. aid and the target of dozens of U.S. sanctions.