Ed Luce comments on American elite anxiety over the possibility of “Brexit”:

Washington’s elites rightly fear that Brexit could spark a chain reaction that could lead to the disintegration of the EU. That, in turn, could trigger the collapse of the transatlantic alliance. US global power has always been magnified by the strength of its alliances. The self-inflicted isolation of America’s closest European ally could be the start of a great unravelling.

Neither of these scenarios seems all that likely. If the British vote to leave (and assuming the government honors that decision), it makes sense that some other EU members will hold their own votes on whether to stay in, but it doesn’t follow that those votes will yield the same result. It definitely doesn’t follow that the governments of those countries would respect the results if the voters came up with the “wrong” answer. It is more often the case that an EU government will ignore an outcome of a referendum it doesn’t like, wait a little while, and then ask the question again when conditions seem more likely to produce the result they want.

Sometimes the “pro-European” argument against British withdrawal makes the EU sound more like a prison than the Euroskeptic criticisms do: we can’t let the others see that there is a way out, or else everyone will want to escape! Britain is also better-positioned to leave than many others because of its own economic and political clout, so exiting the EU may not be so attractive to many of the smaller members. Even if British withdrawal did encourage other states to do the same, it wouldn’t necessarily be so bad. Contrary to what its boosters imagine, the peace and prosperity of Europe do not hinge on the EU’s survival, but it is more likely than not that almost all of its other current members will withdraw from it.

Speculation about “the collapse of the transatlantic alliance” is just that and nothing more. There is no reason why NATO would break up if the EU started to do so. There doesn’t appear to be any desire on the part of any European NATO member to leave the alliance, and there is no reason why states that leave the EU would suddenly acquire that desire. Raising the possibility of the collapse of the alliance is just another way to try to browbeat British voters into voting “In” when it looks increasingly likely that they will go the other way.