A Moment of High Peril
Vladimir Putin appears to be running short of men and materiel in Ukraine. He may be about to play dirty.
The battered city of Kharkiv, Ukraine's second most populous, is showing no signs of falling. The column of Russian armour outside Kyiv has gone to ground. The capital itself seems to be off Moscow's menu entirely, at least for now.
In the Russian capital FSB chiefs are reported to be under house arrest. The economy is in freefall. There are rumours swirling of a potential coup d'etat.
Nearly four weeks into Russia's full-throated attempt to seize Ukraine, things are not going the Kremlin's way. Volodymyr Zelensky, a former comedic actor leading a country that has long been considered an also-ran, has bloodied Putin's nose.
But far from this being a time to relax, or, even worse, fall into self-congratulation, we are now entering a period of high peril.
Two realities are converging to make this so. The first is that Vladimir Putin is not a man who is used to losing. He has always maintained that history punishes the weak.
An oft-quoted story he told in an early biography is of how, while chasing rats through his Leningrad apartment block, he made the mistake of cornering one of them. The rat apparently flung himself at the young Putin.
The second is that - if the military experts are right - the Russian Army may soon run out of the men, materiel, and possibly morale it needs to continue to wage a vigorous multi-front offensive in Ukraine.
If that happens Putin will have to chose between cutting a deal that he can sell at home - and the prospects for that look fairly slim - or escalating. If he escalates, the menu available to him is nothing short of terrifying.
During the Cold War, when the Soviet Union and the West both bristled with nuclear weapons, there were moments of heightened danger.
Th 1962 Cuban Missile Crisis brought the two superpowers to a nuclear stand-off, only defused when the Soviets backed down, apparently in exchange for a promise that the US would withdraw Jupiter nuclear warheads from Turkey.
But for most of its four and a half decades there was a tacit understanding in both Moscow and Washington of the other side's red lines. Meanwhile the prospect of Mutually Assured Destruction kept even the itchiest fingers away from the nuclear buttons.
By the time the Soviets were in rapid decline they were, thankfully, led by Mikhail Gorbachev, a man who had no interest in visiting destruction on anybody.
Today, however, as Russia and the West once again face off, the tripwires are far more difficult to discern.
On the Russian side Putin has proved to be a master of ambiguity which may have served him well in keeping westerners, and even his own generals, guessing in the lead up to the attack on Ukraine.
But it has also produced a whole smorgasbord of western interpretations as to how far is too far when it comes to pushing back.
This was evident during the debate earlier this month on whether the Americans should provide Polish MIG fighters to the Ukrainian air force. The Biden administration ultimately chose the path of caution and scuppered the initiative.
Part of the problem is that Putin - as is his wont - has been sending out conflicting signals. In the last several weeks the Kremlin has at different times suggested that it would put up with different levels of interference from the west.
Arms shipments to the Ukrainians seem to be ok, although the Russians reserve the right to target the convoys. Economic sanctions are apparently also below what might trigger a full military response against the West.
But not only have these thresholds not been clearly articulated, they are also almost certainly subject to revision as the war in Ukraine progresses.
The West, for its part, is also far from agreed on what it will tolerate from Putin. Biden has reiterated that an attack on any Nato member would be a casus belli. But what if the attack was small, or apparently in error, or hybrid in nature. Would that trigger a shooting war between Russia and Nato?
Who of the western leaders is really ready to fire the starting gun on World War 3 in order to defend Riga, for example? I suspect even Biden doesn't know the answer to that.
And there are other more complex - and more probable - scenarios. What if the Russians, who have already pounded Mariupol back into the Stone Age, resort to the use of biological or chemical weapons?
Would the use of such weapons, which would inevitably lead to a wave of western revulsion, trigger an aggressive response? Would the MIG deal suddenly be back on the table? Or even a Nato-enforced no-fly zone?
Biden's trip to Europe this week is designed to flesh out just how far the West will go.
One big problem  for the West is that we all still have one mental foot in the pre-War world. For most of us the war's effect are consigned to the TV, our iPhones, and the price of fuel.
But logic now dictates that our reality is more dangerous than we perceive. Most military experts think Putin will sooner or later lose the war in Ukraine unless he changes the dynamic. Most Russia experts agree that Putin will not accept walking away with such a loss.
To use a football analogy, Putin may just be tempted accept a score-draw that involves Ukraine ceding territory and declaring neutrality. But the day after the deal looks bleak for him at home with a plunging economy, a semi-rebellious oligarchy, and whisperings that he has lost his touch.
The Ukrainian Security Service has begun circulating rumours of a Kremlin coup in the offing involving Alexander Bortnikov, the head of the FSB. While this is likely to just be part of their psy-ops, such an eventuality will be preying on Putin's already febrile mind.
Putin must be aware that if he continues to miscalculate he may be deprived of his job, perhaps his liberty, and possibly his life.
With the exception of Afghanistan - the runaway champions when it comes to defeating superpowers - Russia has not lost a foreign war in a century.
In that sense this conflict is already existential for him - and, therefore perhaps, in his thinking, for Russia. He is, after all, the Tsar.
And an existential threat for Russia, according to its own published military doctrine, is grounds for using nuclear weapons.
Does that mean that an all-out nuclear war with the West is probable?
No. But one gloomy possibility is that the Kremlin may decide to use tactical nuclear weapons - short range missiles carrying a nuclear warhead - to try and break Kyiv's will.
And there is an even darker cloud that has appeared on the horizon. It is far off and most likely will pass us by but nevertheless needs noting. An option openly discussed in Russian military doctrine is the use of a one-time strategic nuclear strike.
This, according to a retired member of the Russian military, would be designed to "show intention." Some variants of the plan call for it to be fired into empty terrain, others for its use against enemy troops.
Ever since the Russian tanks rolled into Ukraine, the spectre of a swift win for Putin was alarming, not just for Ukraine but for anyone who believed, as I do, that he would not have stopped there.
But the prospect of Putin bloodied and taking punches was an even more worrying prospect.
Putin may not be quite on the ropes yet, but he is certainly in a corner. And the gloves may be out to come off.
Please write in with comments, corrections and questions. A version of this appeared on the Spectator website.
Thoughtful perspectives. Much appreciated.