It was definitely one of the stranger moments during an already bizarre press conference given by the President yesterday. When Joe Biden was asked what we planned to do if Vladimir Putin goes ahead with an invasion of Ukraine, his ambiguous answer could easily be interpreted in the favor of Russia. He told the press corps, “It’s one thing if it’s a minor incursion and then we end up having to fight about what to do and not do.”

This appeared to stun even some members of the generally docile and supportive press pool. How would President Biden define a “minor incursion” for these purposes? And who is the “we” that would be “fighting” as a result? The Wall Street Journal took note of this apparent slip-up and pointed out that Putin could easily take that as an invitation to move forward with the invasion once the ground is sufficiently frozen over, as long as he doesn’t go too far.

Mr. Biden didn’t help deterrence at his press conference Wednesday by suggesting that a “minor incursion” by Russia might not trigger a united response from the West. “It’s one thing if it’s a minor incursion and then we end up having to fight about what to do and not do,” Mr. Biden said. Pressed on the point, he didn’t provide any clarity on what would be “minor,” and Mr. Putin may think he now has leave to take at least some territory.

This response fits the pattern that goes back to the weak Western responses to Russia’s previous aggression. In 2009, after Russia’s invasion of Georgia the previous year, Barack Obama called for a “reset” with the Kremlin and achieved little. In 2014 Mr. Obama and Europe imposed sanctions on Russia, but they were too weak to make much difference.

The Biden Administration is now promising “massive consequences” if Russia invades again, but why should Mr. Putin believe it? The U.S. has ruled out any direct U.S. military defense of Ukraine, so Mr. Putin knows he needn’t worry about that. But the U.S. has also failed to raise the costs of a Russian invasion by adequately arming Kyiv.

If the United States is supposed to be taking the lead in finding a peaceful resolution to this standoff, with our NATO and other European allies following our lead, everyone is pretty much in the dark at this point. Biden’s response to that question clearly implies that there is some level of incursion into Ukraine by Russia that wouldn’t be met with “massive consequences” and he anticipates infighting between our allies as to what to do about it. Why would anyone in Europe stick their necks out to defend Ukraine if the United States might not have their back?

Also, it’s unclear what Biden meant by a “minor incursion.” How is anyone supposed to define that? Does he feel that it’s okay for Russian tanks to roll over the border and seize some territory provide they don’t take “too much” of Ukraine’s land?

That’s not how this game is played. You’re either keeping your troops in your own country or you are invading if you send your military across the border without an invitation. It’s pretty much the same as the definition of rape in Article 120 of the Uniform Code of Military Justice. “Penetration, however slight… is sufficient to complete the offense.”

Our reputation as a military power took a serious beating after the botched withdrawal from Afghanistan. We left both our allies and our adversaries with the impression that we were retreating back to our own borders and wouldn’t be engaging enemies who become militarily aggressive. Joe Biden doubled down on that image when he essentially took a military response in the defense of Ukraine off the table, saying that we would only respond with economic sanctions. (The Russians are currently laughing at our sanction threats.)

If Vladimir Putin was waiting for an ideal time to take over Ukraine by force, he probably couldn’t pick a better one than the current era. If he’s certain that the United States will remain on the sideline, our NATO and other European Allies aren’t going to take on Russia without us. Everyone will wind up simply clucking their tongues, tossing out a few sanctions, and Kyiv will wind up being just another suburb of Moscow.

Just to be clear, I’m not arguing in favor of America going to war with Russia, particularly that close to their own territory. But if we’re going to keep bad actors from acting badly, they should at least be forced to consider a credible threat that our military might move against them. Joe Biden has removed that credible threat and Russia may just wind up absorbing Ukraine this winter. If they do, you can bet that China will be watching carefully and factoring these developments into their future plans for Taiwan.