It’s not the only part of Russia’s war machine that has malfunctioned, but this could be the worst of outcomes if it can’t get back underway. The 40-mile convoy into Ukraine had signaled a new all-or-nothing resolve from Vladimir Putin, an escalation to massive urban combat rather than the initial shock-and-awe campaign to force a capitulation of Kyiv. However, as the Washington Post reports, the convoy has stalled out for more than a day — making this major Russian force a long line of sitting ducks, at least at the moment:

U.S. and British officials said a long column of tanks and combat vehicles was stalled roughly 20 miles north of central Kyiv on the sixth day of President Vladimir Putin’s invasion, deepening questions about whether Moscow’s assault will yield a protracted war of resistance with its much smaller, less powerful neighbor.

The convoy, stretching some 40 miles, has moved little over the past day as the Russian forces have grappled with fuel and food shortages, a U.S. defense official told reporters, speaking on the condition of anonymity to discuss a sensitive situation. The British Defense Ministry said Ukrainian forces continued to hold the cities of Kharkiv, Kherson and Mariupol, but all three “are now likely encircled by Russian forces,” with air and artillery attacks intensifying. …

Officials say Moscow has now pushed into Ukraine more than 80 percent of the combat power it staged within Russian border areas and in neighboring Belarus in recent months, demonstrating Putin’s determination to cripple a Western-backed government that he maintains has undermined Russian security.

A long, thin line of forces makes for a very attractive target, especially from partisans with more mobility, better terrain knowledge, and much higher morale. That kind of communication line either has to keep moving or have highly mobile flank protection to survive. Thus far, however, Russian forces haven’t exhibited even basic tactical competence, let alone Clausewitz-like imagination. The fact that the main convoy has run out of fuel all but eliminates the possibilities of mobile flank protection, even if Russians had shown any such inclination while their armor has had enough gas to move.

If the Ukrainians had better air competitiveness, this convoy would be a small-scale equivalent to Napoleon’s grand armée going into Russia. As it is, they’re still vulnerable to smaller scale attacks that could freeze both ends of the line and trap troops and assets in a killing zone unless Putin can find a way to get them moving again.

There have been some signs of units arriving on the outskirts of Kyiv, as a siege apparently is Putin’s next move to force capitulation:

Russian forces Wednesday pressed ahead with a wide-ranging but slow-moving offensive targeting key Ukrainian cities, menacing the capital of Kyiv with a miles-long military convoy, launching deadly strikes on the second-largest city of Kharkiv and apparently breaching a strategic Black Sea port city with tanks and troops. …

With President Biden vowing in his Tuesday night State of the Union address to make Russian President Vladimir Putin pay a heavy price for the unprovoked attack on Ukraine, its defenders — a motley mix of regular army troops and ad hoc civilian militias — braced for an expected full-scale attack on Kyiv, a city of 3 million people.

Ukrainians have been bracing for that siege for a few days now, thanks to widespread coverage of the convoy. The more time Kyiv has to prepare, the better they can defend the city, which is another way in which this stall is a particularly bad development for Russia’s military. We have already seen that the morale in the invasion force isn’t high, and at least some reports show that Russian commanders didn’t even prepare their conscript-heavy forces for a war at all. A protracted urban assault on Kyiv will have reluctant and untrained invaders going up against native forces filled with angry, motivated, and in some cases already-tested Ukrainian regulars and militias fighting for their own country. That will turn Kyiv into a Stalingrad for Putin, only with the KGB colonel playing Adolf Hitler’s role.

Can Russia still win such a battle? Brute force and overwhelming numbers will make a difference here, but the better question is what they will “win” even if they seize control of Kyiv. They will have “won” static positions in obvious places that the citizenry knows better than the Russian army does, which will turn occupiers into sitting ducks for years of insurgencies — assuming Russians can hold out even that long.

And right now, Russia can’t even provision their forces properly for a drive on the highway. The longer that convoy stalls, the fewer forces will make it to either end of that line of communication, and the better odds Ukrainians have of outlasting Russia.