Leslie Gelb makes a very dubious assertion:

Whether the White House admits it or not, foes the world over seem to have concluded that Obama has taken the U.S. military force option off the table and made aggression easier.

Gelb doesn’t have any evidence for this, or if he does he hasn’t bothered to produce it. He complains that Obama is giving Putin a “free ride” by acknowledging that Russia is not going to be forcibly expelled from Crimea, but no one seriously thinks that this is a practical or desirable option. Whatever flaws Obama’s response has had, not threatening military action isn’t one of them. Gelb goes on to say that Obama is “walking away” from the Budapest Memorandum, which is just another reminder that most people that refer to this agreement don’t really understand what it does and doesn’t require of the U.S. Is it “perfectly obvious that Kiev never would have given up its nukes unless it believed the U.S. would come to its defense in some meaningful fashion”? I don’t think so. Ukraine could not have afforded to keep the nuclear weapons that were then in its possession in any case, and we must be kidding if we think that Moscow would have ever permitted so many nuclear weapons to remain in the hands of an unstable government next door to Russia. It is rather more obvious that the U.S. wasn’t prepared to come to Ukraine’s defense militarily in the 1990s, and if anything this should be even more clear today. The “plain meaning” of the memorandum is that the U.S. and U.K. pledged to bring violations of the agreement before the Security Council, and they committed to do nothing more than that. The U.S. can’t renege on a promise that it never made.

In the case of Ukraine, I’m not sure that it matters that the U.S. ruled out the use of military force, because no one–least of all the Russians–would believe that the U.S. will force against Russia over Ukraine. Acknowledging what all sides know to be true hardly gives anything away. More important, making threats that are obviously empty achieves nothing and puts the U.S. in a worse position than it was before. Pillar makes this point in his article on deterrence:

If the other side does not believe the threat ever would be executed because doing so would be highly costly and damaging to the side making the threat, there again is no deterrent value [bold mine-DL]. Such threats are worse than useless, because they risk exposing us as bluffers. Any show of military force by the United States in the vicinity of Ukraine (not the minor redeployments that merely provide some reassurance to Poland and the Baltic states) would exhibit this problem, given the patent folly for the United States to engage in a war with Russia, especially in Russia’s backyard and especially given the much greater importance to Russia than to the United States of the distribution of power in this region [bold mine-DL].

Gelb says later that the “worst thing to do is bluff,” but there is no way that the U.S. could threaten the use of force in Ukraine without making everyone think that the U.S. had to be bluffing. At best, this means issuing an empty threat that doesn’t escalate into a direct conflict, which is exactly what Gelb says he doesn’t want. At worst, it means making a major war more likely, which no sane person should want. Gelb keeps talking about making “credible force” an option, but there is no way to make a military threat over Ukraine seem credible when it would be wrong to issue such a threat and completely insane to carry it out.