By Andreas Kluth / Bloomberg Opinion

One-against-many usually suggests the many have the advantage. But in international relations and grand strategy, that’s not always the case. Sometimes the one prevails, provided he (in this case it’s a he) is ruthless enough and keeps the many divided.

He, of course, is Russian President Vladimir Putin. As he contemplates how to harass, subvert, subjugate and re-invade Ukraine, he must constantly keep in mind the response by his overarching foe, the West. Putin’s advantage is that he can decide whether, where, when and how to act. By contrast, it’s not clear who decides for the West; or even whether it’ll be able to decide at all.

In my previous analyses of this geopolitical clash, I’ve repeatedly used “the West” as shorthand for a notional geopolitical grouping. It consists of NATO, the transatlantic alliance of 30 nations; the European Union, all but six of whose 27 member states are also in NATO; and sometimes even countries such as Japan or Australia that are outside of both organizations and in the geographic east.

Of course, calling these countries “the West” sidesteps the reality that they are far from a coherent bloc. They differ in how they perceive the threat from Russia and their own vulnerabilities; and hence their national interests.

None other than Joe Biden, president of the U.S. and, thus, theoretically the West’s preeminent leader, just acknowledged this potential for disunity. Of course, the West will answer Putin’s aggression, he said this week. But what’s the definition of aggression? “It’s one thing if it’s a minor incursion and we end up having to fight about what to do and not do,” he said. Guess who was listening closely (and gleefully) in Moscow.

The Europeans, as is their wont, seized the opportunity to make the confusion worse. Addressing the European Parliament, French President Emmanuel Macron surprised everybody by calling for the Europeans to “conduct their own dialogue” with Russia. And no longer coordinate with NATO and the U.S.? This certainly rhymes with Macron’s neo-Gaullist pretensions about European “autonomy” and “sovereignty,” which is usually code for acting independently from the Americans. But it certainly won’t impress Putin.

The role played by the EU’s largest country, Germany, is also iffy. Its new government coalition is split. On the unambiguously pro-Ukraine, pro-Western and anti-Putin side are the Greens and the Free Democrats. But the Social Democrats of Chancellor Olaf Scholz are internally divided, because they contain a large faction of Russophiles and Putin appeasers, who remain wedded even to the idea of a new gas pipeline between Germany and Russia.

In an echo of Macron, German diplomats now want to revive the “Normandy format” of separate talks including Russia, Ukraine, France and Germany (so called because they first met as a group during the D-Day celebrations in 2014). That could help if the negotiations are coordinated with the U.S., NATO and EU; or hurt, if not.

The EU is its own hairball of potential disunity. That starts with the coming decisions to impose new sanctions. The bloc nominally has a Common Foreign and Security Policy. But this policy has to be decided unanimously; any member nation can veto anything.

After Putin’s annexation of Crimea in 2014, the EU hewed reasonably well to a common line. But as Russia becomes increasingly hostile and the conflict drags on, fissures are likely to open. Members such as Poland and the Baltic and Scandinavian states see Putin’s menace as existential and will want a tough line. Others, such as Greece, Hungary or Cyprus may emphasize other priorities.

Putin knows all this. Sure, he could overwhelm Ukraine in a blatant show of force. But my bet is that he’ll be more conniving than that. He’ll launch a limited strike against Ukraine while needling the West everywhere at once and all the time, from outer space to cyberspace, with disinformation campaigns and reality distortion fields, by sending desperate migrants to the EU, dispatching “little green men” and staging false-flag incidents, and yes, even by deploying troops.

What are we going to call these different and varying assaults? Incursions? Skirmishes? Invasions? As Biden said, we’ll probably end up fighting about definitions for months, and then reach very different conclusions. This is the West’s greatest weakness. Leadership — in both North America and Europe — now means recognizing that, and then doing everything possible to turn the many into one.

Andreas Kluth is a columnist for Bloomberg Opinion. He was previously editor in chief of Handelsblatt Global and a writer for the Economist. He’s the author of “Hannibal and Me.”