How many technologies are you aware of that don't have a harmful potential application? I mean, (electronic) computers were invented for military purposes and can enable all kinds of mischief on the Internet. Refrigeration makes military logistics a lot easier. Hell, internal combustion drives tanks and other military vehicles. GPS makes cruise missiles easier, but pre-GPS ICBMs just used inertial targeting; that's close enough for thermonuclear bombs.

In HPMOR, Harry figures out a large number of ways to make weapons out of the materials present in a low-tech classroom. I doubt anything short of reducing the world to subsistence farming (and no more than that) is sufficient to bring about a state in which

"... no nation will be in a position to commit an act of physical aggression against any neighbor"