The chief threat to the security of the U.S. is no longer a rival superpower. Today, America is immediately threatened by terrorist groups, especially if they seek to use nuclear, biological, and chemical weapons against our nation. Preventing the proliferation of these deadly weapons and their delivery systems, and reducing the number of those already in existence, is therefore a top priority for the Department. The Department is also seeking to bolster the international arms control regimes that counter weapons of mass destruction (WMD), including by pressing for rigorous compliance with their requirements. The security of the U.S. depends upon the vigilance and skill with which the U.S. Government protects its citizens against this dire threat. The Department is a key leader in this struggle.