The argument would be that certainty of an invasion of Ukraine prompting an American military response, or a Ukrainian nuclear one, would have deterred the Russians from carrying out the invasion in the first place.<p>This is of course arguable, since it rests on a counterfactual. But given the pains Russia took to camouflage their invasion as a domestic uprising (see <a href="http:&#x2F;&#x2F;www.bbc.com&#x2F;news&#x2F;world-europe-26532154" rel="nofollow">http:&#x2F;&#x2F;www.bbc.com&#x2F;news&#x2F;world-europe-26532154</a>), it seems at least plausible, since the only reason for them to disguise their involvement would have been to reduce the risk of retaliation.