The El Paso brand of deterrence is just as much directed at smugglers as immigrants, if not more so.
Ahmadinejad has a point: the deterrence policy has contributed to the escalation of the nuclear arms race.
Overall, the deterrence was perceived as adequate and, most importantly, cost-effective.
A military capability sufficiently strong to discourage any would-be aggressor from starting a war because of the fear of retaliation. (See balance of terror.)