John Adams wrote in his diary

I had something to say about Advizing the States to institute Governments, to express my total despair of any good from the Petition or any of those Things which were called conciliatory measures. I constantly insisted that all such measures, instead of having any tendency to produce a Reconciliation, would only be considered as proofs of our Timidity and want of Confidence in the Ground We stood on, and would only encourage our Ennemies to greater Exertions against Us.

While I recognize that he was speaking of the acute issue at hand (how long to wait for a peaceful solution to the splintering of the American colonies from Great Britain in 1776), his observation is applicable to both other historical situations as well as to those which we face today.
It is nothing new to say that effective diplomacy is supported by the plausible threat of force. Jefferson realized this in his “dealings” with the Barbary Pirates in America’s first encounters with Muslim “non-state actors.” World War I was an example of what could happen when an overweaning desire for peace blotted out the wisdom of maintaining the requisite arms to safeguard it.
However, after the Cold War, the idea of arms undergirding diplomacy appears to have been deemed antiquated by many nations. To crib from one theorist, Europe and America prematurely and mistakenly began to believe that the theories of their very “Kantian” world was extending into places in which the reality was a very “Hobbesian” conception of the sovereignty of nations and their power. Yet, when 9/11 ocurred, the U.S.–if not Europe–reconceived of the wisdom and necessity of using force again. The lead up to the Iraq war only solidified this epiphany as it exhibited the folly of relying on the process of diplomacy without any serious threat of violence. If there is only process without consequences, then the process would end because of lack of interest and nothing more. Indeed, with the Oil-for-Food revelations and all of the related corruption, it seems that was the goal all along.
But the root of the attitude that diplomacy can occur without the threat of force may be linked to a changing conception of sovereignty whereby anyone who can claim and hold power is deemed legitimate, democratic or not. However, as Andrew’s very good piece concerning recent events concerning Syria indicate, perhaps such conceptions are changing. It may be that the events in Europe of the past year have helped to quicken the pace as more realize that patronization will get them nowhere with those who don’t think “reasonably.” Perhaps more are realizing that the only way to get some to the bargaining table is with an olive branch in one hand and a big stick in the other.