Trying to prevent terrorists from obtaining nukes should be national security priority number one. But the Obama administration’s plan to combat that threat is puzzling. They’ve argued ad nauseam that arms reduction treaties like START are the key to keeping loose nukes out of the hands of terrorists. That’s absurd. START limits nuclear weapons on bombers, submarines, and ballistic missiles — these bombs are large and restrained by failsafe mechanisms and unlock values which make them nearly impossible to detonate. In six decades of nuclear custody, there has never been a theft of such a device in either the United States or Russia (though a few have been lost, mostly in bomber crashes during the 50s and 60s).

Loose Russian bombs are a concern, considering their massive inventory of tactical nuclear weapons. Since tac nukes are easier to pilfer, Pentagon officials have expressed concern about the accountability and security protocols for handling these weapons. But Mr. Obama’s prized new treaty doesn’t touch Moscow’s small yield weapons, only limiting long range strategic bombs and their delivery systems.