In his Nov. 16 op-ed piece, “New Threats, Old Weapons,” retired Adm. Robert R. Monroe said that to have a more effective deterrent against rogue states and terrorist groups, we need a new generation of nuclear weapons.

His notion that a leaner nuclear arsenal will deter rogue states and terrorist groups from using nuclear weapons to harm us presumes that we are dealing with reasonable adversaries. Given the tactics that terrorists use, that is a naive assumption.

Further, the Bush administration’s January 2002 Nuclear Posture Review stresses the importance of being prepared to use nuclear weapons in an offensive manner and against a wider range of countries, even those that are not nuclear. In my view, the president’s initiatives to develop additional nuclear weapons are not about deterrence but about adding a tool to our military arsenal.

Adm. Monroe said that we must have nuclear weapons with “greatly increased accuracy,” “specialized capabilities” and “tailored effects.” But according to Stanford University physicist Sidney Drell, the effects of even a small nuclear bunker buster would be disastrous. A one-kiloton weapon detonated 20 to 50 feet underground would dig a crater the size of Ground Zero and eject a million cubic feet of radioactive debris into the air.

Our reopening the nuclear door to a new generation of weapons will only encourage proliferation. Russian President Vladimir Putin’s recent statement that Russia is developing new nuclear missile systems is testimony to that effect.

This year Congress eliminated funding for new nuclear weapons programs in the recent appropriations bill. This was the right move because, to make our nation safer from nuclear threats, the best investment we could make is to secure nuclear materials at facilities around the world while insisting that other nations follow us down the path of nonproliferation.

Dianne Feinstein U.S. Senator (D-Calif.) Washington