Justin Logan ably covers  familiar ground in his explanation of why there are no isolationists in America:
The second thing you should know is that “isolationist” was designed as a slur and remains one. No one calls himself an isolationist.
As I’ve noted before, the label continues to be useful to hawks because its meaning can be changed to suit almost any argument. One can be a mostly conventional internationalist, accept the U.S. role in the world as it is today, support most U.S. wars, and still be attacked as an isolationist if you fail to endorse a maximally hawkish foreign policy. The most common use of the slur is to attack critics of whichever ill-conceived military action happens to be under consideration at the moment, but it can also be applied liberally to skeptics of government surveillance and detention, advocates of military spending reductions, or opponents of cruel and pointless sanctions policies. Thiessen’s column  today was overflowing with references to “isolationists” and “isolationist retreat,” and it serves as a helpful guide to how the word is used to insult the people it supposedly describes. Thiessen uses the recent Paul-Christie quarrel as one of his examples:
Christie was absolutely correct when he called Paul’s isolationist views “dangerous” and challenged him “to come to New Jersey and sit across from the [Sept. 11] widows and the orphans and have that conversation.”
As I have said , Christie didn’t attack Paul for his “isolationism,” but for his libertarianism, and this is the word he wanted to use. He was defending NSA surveillance activities against an effort to rein in those activities a little. Not only did Christie never mention the i-word, but his criticism would have been even more inaccurate and demagogic than it was if he had. Notably, Thiessen never identifies which of Paul’s views are isolationist, nor does he explain why they are dangerous. Simply using the word isolationist is a shorthand to convey contempt, fear, and warning all in one without ever having to confront the specifics of the views the person holds. One of the chief uses of the isolationist slur is to avoid a debate on the substance of any particular policy, and to lump any and all skeptical arguments together with the “isolationist” bogeyman.