Will ‘boots on the ground’ be the next red line crossed in Ukraine?

As formerly firm limits on escalation have been discarded in the interest of ensuring Ukraine’s survival, the most inviolable from the outset has been the prohibition against deploying Western troops. Now that bedrock prohibition looks shakier than ever, as France considers sending military trainers.

If it does, the consequences could be graver and less predictable than those arising from past incremental steps providing Kyiv with one weapons system or another that had previously been denied. Yet there’s no unity among Ukraine’s NATO allies regarding putting boots on the ground in Ukraine. And there’s little sign so far that France and the handful of other European countries weighing the decision, including smaller allies like Estonia and Lithuania, have reckoned with how it might unfold.

Washington, Berlin and other major partners in Ukraine’s defense have ruled out deploying troops for two main reasons.

The first is that it would represent a quantum escalatory leap — not just heavy metal to buttress Ukraine’s defenses but manpower and the potential for casualties among European troops. The second is the political value in selling Kyiv’s cause to Western publics — that is, as a war whose massive cost in lives has been borne by Ukrainians, and Ukrainians alone, to protect Europe itself from Russian aggression.

Biden’s determination to back Ukraine while also avoiding World War III has resulted in self-deterrence — foot-dragging on sending Ukraine long-range missiles, fighter jets, air defense systems and other weapons that might have toughened Kyiv’s capabilities on the battlefield and saved lives. But the president’s gradualism has also exposed as empty Moscow’s nuclear threats in response to the provision of ever more powerful Western arms.

A few Western allies have undertaken small training missions inside Ukraine over the past two years. What French President Emmanuel Macron is now contemplating seems more ambitious, more public and more risky — even if the trainers he might deploy would be far from the front lines.

It is grounded in his view that the West would be better off keeping the Kremlin guessing about what it is prepared to do, rather than ruling out what it will not do. By shifting to a posture of “strategic ambiguity,” Macron seems to think, Ukraine’s allies could move beyond self-deterrence, shifting to Putin the burden of calculating the risks of escalation.

“I would be hard-pressed to assume Putin would deliberately want to go into direct hostilities with a NATO power when that power would not be engaged in an act of war,” said Francois Heisbourg, a prominent French analyst who supports Macron’s approach.

The trouble is: What if Putin calls Macron’s bluff? Especially given that the French leader has done almost nothing to prepare domestic public opinion for body bags coming back from Ukraine. Not to mention the fact that most of France’s major NATO allies, which remain adamantly opposed to troop deployments themselves, would be unlikely to seize on French casualties to seek a more direct confrontation with Russia.

In fact, Putin might see hitting French troops, if Russian forces can locate them, not only as a way to expose Western divisions but also as a chance to humiliate Macron, now among the most hawkishly anti-Russian Western leaders.

“We support Ukraine,” Heisbourg told me. “Does that provide an element of risk? Yes, it does.”

France has formidable armed forces and is among the world’s leading arms makers. But it remains unclear what added value France could offer Kyiv’s battle-tested military after more than two years of holding off Putin’s onslaught. At this point, the French themselves may not know.

What is known is that despite Macron’s tough rhetoric, Paris’s deliveries of what Ukraine needs most — weapons systems and munitions — have lagged behind that of many of Ukraine’s other NATO allies.

France has supplied a few dozen long-range SCALP missiles, which were important in breaking Moscow’s blockade of Ukrainian shipping in the Black Sea, among other arms. Yet in terms of total bilateral military aid to Kyiv, France ranks behind the Netherlands, Denmark and Poland, not to mention bigger donors such as the United States, Germany and Britain.

Reports suggest Macron could announce his plan to send military trainers on the 80th anniversary of D-Day, on Thursday, when Biden and other Western leaders will join him to commemorate the landings in Normandy. In a ceremony marking Allied unity, the French leader risks highlighting his isolation — and with the prospect of precious little benefit.