In his first year as president, Mr. Bush unilaterally withdrew the United States from the 1972 Anti-Ballistic Missile (ABM) Treaty, which had been designed to preserve the longstanding regime of "mutual assured destruction" by denying either the US or the former Soviet Union the ability to launch a first strike and survive. Like Mr. Reagan, Bush and other critics of the ABM Treaty believe the US should be able to defend itself not only from Russian missiles but from those launched by North Korea or other "rogue states."
Critics point to more likely threats not addressed by ballistic missile defenses: low-flying cruise missiles or "dirty bombs" filled with smuggled radioactive material.
Still, many see deployment of missile defenses as logical if not required for national security. "The threat has changed since the cold war," says military analyst Loren Thompson of the Lexington Institute. "There are more countries with ballistic missiles, and their behavior is less predictable."
This same concern about a more complicated and more dangerous world also drives the administration's desire to accelerate research on nuclear weapons designed for 21st-century threats. "Nuclear attack options that vary in scale, scope, and purpose will complement other military capabilities [to deter] adversaries whose values and calculations of risk ... may be very different from and more difficult to discern than those of past adversaries," states the Pentagon's most recent Nuclear Posture Review.
That range of options is reflected in the Defense Authorization Bill now being considered by the Senate. It includes $27.6 million for the development of the 100-kiloton bunker buster and $9 million for new "low yield" weapons (less than 5 kilotons, or about one-third the size of the bomb dropped on Hiroshima).