Paul Pillar comments  on the danger of assuming that threatening a military attack usually “works” to intimidate the other government into making concessions:
The situation most often invoked, of course, is Iran and the issue of its nuclear program. The simplistic belief about the supposed universal efficacy of threats of military force thus accentuates an already widely held and mistaken assumption that the more that Iranians fear a military attack the more likely they are to make concessions about their nuclear activities.
The assumption Pillars mentions here is so widely-held because many Americans fail to see how threats of military force are received and understood by the targeted regimes and nations. The Iranian government and most Iranians believe their nuclear program to be entirely within their rights under international law, so it is very unlikely that the government can be coerced into making major concessions to Western demands on this issue. Because the U.S. has been threatening Iran with an attack for years, this has almost certainly made the Iranian government less accommodating and less likely to trust the U.S. to negotiate in good faith. Repeated threats have probably made the acquisition of nuclear weapons appear more attractive than it otherwise would be. While many in the West assume that negotiations won’t succeed unless there is a military option available, this fails to recognize that the threat of attack makes it virtually impossible for a targeted government to reach an agreement without appearing to have surrendered to a hostile foreign power.
Among the reasons that threats of armed force often not only do not work but may even be counterproductive—stiffening the resolve of the decision-makers on the other side—is that regimes do not like to be bullied.
One of the many unwelcome side-effects of exaggerating foreign threats to the U.S. is that many Americans sometimes seem to forget how great the disparity in power is between the U.S. and the states that are often held up as major or even “existential” threats. If Iran is mistakenly perceived here as such a great threat to America, many Americans won’t see U.S. actions designed to punish and threaten Iran as aggressive and heavy-handed tactics. However, that is how they appear to most people on the receiving end. The common response of any nation and any government to such tactics is to harden their opposition to foreign demands. Nothing is less likely to persuade Iran to make concessions on the nuclear issue than the threat of attack, but there seems to be nothing that Iran hawks worry about more than making that threat as “credible” as possible. As I’ve said before, Iranians have no trouble believing that the U.S. will sooner or later attack their country. What many of them may have difficulty believing after the last twelve years is that the U.S. might be willing to accept a diplomatic solution.