And yet Washington’s seemed reluctant to provide Ukraine with the weapons it would need to meet that goal. Last month, U.S. President Joe Biden agreed to send M-1 Abrams tanks, only after Germany refused to send its Leopard 2s without the Americans pledging their commitment first. This year, the U.S. will spend more than US$815 billion on defense, further developing what’s already the most powerful military in the world—with the most cutting-edge aircraft, tanks, missiles, ships, and logistics tools. By all appearances, if their strategy were truly focused on repelling Russian forces and re-establishing Ukraine’s internationally recognized borders, the Americans could supply Kyiv with much more war materiel. So what is the U.S. strategy in Ukraine, exactly?

Rob Lee is a senior fellow with the Foreign Policy Research Institute’s Eurasia Program and a former Marine infantry officer. To Lee, the apparent ambiguities here make sense in the context of America’s competing priorities in the conflict: defending Ukraine and keeping the war from spiraling into regional and global chaos. These aren’t priorities the U.S. can choose, Lee says; they’re written into the situation, and they’re constantly competing with one another. They’re also complicated by Moscow’s disinterest in backing down or compromising, willingness to feed unlimited civilian conscripts into the war, and, so far, freedom from domestic consequences—whether for the popularity of the war or for the Kremlin’s continuing grip on power.

Rob Lee: We know it’s driven by two priorities. One is to prevent Russia from defeating Ukraine. The other is to prevent any escalation of the war that broadens it and brings Russia into direct conflict with NATO.

But we also know these are competing objectives. As much as the U.S. and its Western allies would love to see them realized together, they’re separate.

For example, if Ukraine were to succeed to the point where it was able not just to defend the territory it held when Russia invaded last year but to push back into Crimea—which the Russians annexed in 2014—the U.S. would see that as carrying the risk of a nuclear escalation from Moscow. Similarly, if Russian forces were to get routed and start collapsing, and Moscow were to see itself as facing domestic and international humiliation, that’s a scenario, too, that could potentially trigger a nuclear escalation.

Neither scenario would necessarily mean a nuclear escalation is likely. But even if it were very low-probability, the U.S. would still have to understand it as very high-risk—as potentially catastrophic on its own terms, and as the kind of event that could force NATO directly into the breach.

What we don’t know is how the U.S. will balance these competing objectives as the war evolves.

Valentine: So, what do we know about how the U.S. is balancing the objectives so far?

For instance, initially, the U.S. provided Javelin and Stinger missiles, which aren’t particularly heavy types of equipment. A lot of artillery only came in April, when Ukraine was running low on it. Heavier missile systems, like HIMARS, which are much longer-range, only came in June, when disparities between Russian and Ukrainian munitions were becoming really apparent. But notably, when the U.S. did provide HIMARS, it emphasized it was not providing ATACMS, which are much longer-range still.

Now, there’s a lot going on behind these calculations, and there’s a lot more going on on the ground while they’re being made, so you can’t read the situation entirely decision-by-decision—whether it’s to provide HARM air-to-surface missiles last summer or, significantly, tanks now. Or for that matter, not yet to provide F-16 fighter jets. You can see the overall pattern, though, as intended to signal to Russia that the U.S. is very serious about supporting Ukraine’s self-defense—but not interested in escalating the conflict any more than it has to.

Valentine: That might suggest the U.S. is leaning somewhat toward the second priority—non-escalation. Are there any patterns pointing the other way?

Lee: There’s reporting that suggests the Biden administration has recently become less reticent to allow Ukraine to strike in Crimea. And Ukraine has done some of that, even if just with commercial drones that they’ve jerry-rigged to use as unmanned kamikaze weapons—but there’s some evidence suggesting a change of thinking in Washington and other NATO capitals about what kinds of weapons can and should be provided, and what the escalation risks really are.

That said, the context for this thinking is fluid. The fundamental reality of the war is fluid. The situation on the ground in Ukraine is fluid; Russia’s response to it is fluid; and so the relative weight of the United States’ divergent priorities is going to be fluid.

Before Moscow decided to mobilize the Russian population through involuntary conscription, for example, the manpower situation was favorable for Ukraine. But once the Kremlin mobilized its population with conscripts, it gave itself a considerable manpower advantage. And it’s an ongoing mobilization—and there just isn’t enough of a domestic backlash in Russia to threaten it. By all appearances, Moscow can keep it up.

So Ukraine may have gotten enough weapons to succeed in the circumstances they were in back in August and September, but once Russia mobilized and gave itself a much larger force—even if it’s not very well-trained—the question became whether the U.S. and the West needed to provide more and qualitatively stronger military capabilities in order for Ukraine to be able to overcome the change in Russian manpower. It’s just one illustration of how the priority of helping Ukraine defend itself is in a shifting tension with the priority of not escalating the conflict.

“Before the war began, Moscow believed it would win fast with overwhelmingly superior capabilities—that the Ukrainians would just accept the invasion, the U.S. and NATO wouldn’t get meaningfully involved, and the whole thing would be wildly successful. Which was all obviously very wrong.  Still, more than a year later, there are no indications that the Russians have limited their ultimate objectives for the war. … Along the way, they’ve held out hope that NATO unity would break …, and that hasn’t happened, either. … So it’s going to be significantly about endurance. And the Russians believe they can endure for longer than Ukraine can—with conscripts, with ammunition—and it’s not obvious that they’ll be wrong as a long war grinds on.”

“The U.S. and the NATO coalition haven’t fought or supplied a real industrial war like this in a long time. In Afghanistan and Iraq, the U.S. obviously used a lot of munitions, but they were munitions the U.S. military could deploy at sustainable rates. A high-intensity conventional war like the one in Ukraine today requires far more artillery ammunition, far more precision-guided missiles—the kinds of thing the U.S. hasn’t had to test its defense industry on in a very long time. For decades, at least, if not going back to the Second World War.”

“In Europe, collective security is stronger than it was before the war. I think there’s a recognition now, among the U.S. and its European allies, that large-scale conventional war isn’t just a thing of the past—and that Russia, in particular, is going to be a significant adversary and threat for the foreseeable future. So we’ve seen Finland and Sweden join NATO; there’s going to be no question in the long term about whether Ukraine will join NATO; and everyone’s relearning the value of hard military power. A lot of the thinking in Washington and the capitals of Europe will be changing about what kinds of surprises they might encounter next and how to be ready for them.”