Donald Trump is not consistent on many things, but he always sticks by Vladimir Putin. Even when forced to concede that Putin might have done something bad, such as ordering murder, he qualifies it.
He goes in for bogus moral equivalence ("Well, I think our country does plenty of killing"). Hillary Clinton, he said in the TV debate last week, is a "nasty woman". But the fact that Mr Putin is a nasty man seems to hold a sort of allure for Mr Trump. Putin "outsmarts" Mrs Clinton, he jibes.
How have we got to the point when a Russian leader can be a role model for someone who might become president of the US? Partly because of American weakness. In the 2012 presidential campaign, the Republican nominee Mitt Romney challenged the incumbent, Barack Obama. When Romney described Russia as a hostile power, everyone smart laughed. What a preposterously Cold War mentality he was exhibiting! Didn't he realise we live in the 21st century?
President Obama and the rest of the West, have done very little in response. His main foreign policy initiatives have been to do with apology - particularly to Muslims - rather than action. If he has intervened, he has usually proved readier to do so against friendly powers. He told the British how to vote in the EU referendum, and has tried to interfere in Israeli elections in order to get more Arabs on the register.
He misunderstood the Arab Spring, let the Syrian disaster happen, and created a vacuum in the Middle East, making space for Isil as well as Russia. This has weakened Western interests in Lebanon, Jordan, the Gulf States and Turkey, pushing some of those countries to seek other partners.
This, in turn, has led to human flight, producing demographic trouble in Europe and the consequent spread of instability across our continent.
Putin happily exploits all this, not just because he is an adventurer, but because he really does not believe in the post-Cold War settlement. In the 1990s, we in the West felt it had all ended happily once, with Russian co-authorship, "Helsinki" human rights and national democratic freedoms had been guaranteed across the formerly Communist Eastern bloc. Putin's Russia rejects this vision. It claims it was forced to accept it in a moment of weakness.
The Russians' view of the world is quite different from ours. They seek a system like that constructed by the Yalta agreement of 1945, in which the globe is carved up into spheres of influence. Within its sphere, Russia would be free to oppress its subject peoples (in Estonia, Ukraine, perhaps Poland) as it saw fit. Putin has challenged the post-Cold War settlement so fiercely that you could almost say there isn't one any more. The rules of the international system have broken down.
In the West, we do not fully understand this. So we either excuse Putin - as do Trump, Jeremy Corbyn and Nigel Farage - as a means of attacking leaders, or we condemn him - as do Boris Johnson and Theresa May - without a clear sense of what to do about it. According to James Sherr of Chatham House, the key thing to grasp is that: "We can't repair the partnership: we must intelligently manage the antagonism."
Sixty years ago this week, Soviet tanks entered Budapest. After a few days of pretending to treat with the anti-Communist Hungarian revolution, they crushed it. Thousands died. This horrible event helped sow the seeds of a resistance which, thanks to Ronald Reagan, Margaret Thatcher, Pope John Paul II and brave dissidents in the East, eventually liberated the Warsaw Pact countries in 1989.
What the invasion of Hungary did not do, however, was create inter- and transcontinental instability. Hungary was in the Soviet sphere, and so the Nato allies were not obliged by treaty to intervene. But in 2016, if Putin decides to invade the Baltic states or Poland, or indeed, Hungary, we are. In this sense, the situation now is more dangerous than it was then.
The Russians can see that we don't know what we would do if they attacked a Nato ally. Putin may conclude that our indecision is so great that he could get away with it. That, after all, is what he has clearly decided about Syria.
Perhaps guessing that Trump will not win the election and that President Hillary Clinton will be tougher against him than Mr Obama, he seems to be going all out to grab what Russia calls "useful Syria" right now. By the time she is inaugurated at the end of January, he will have got what he wants.
The breakdown of the international system is made more noxious by the Russian mood. There is resentment against the West, supported by massive propaganda at home, conveyed in American accents abroad. Perverse though it may sound, this chimes with discontents in the West. Groupings as apparently various as the Front National in France and the Stop the War Coalition in Britain tap in to Putin-esque anger, a process which the Russians actively assist.
In the US, Mr Trump raises this to a degenerate political art-form, in which one of America's bitterest enemies is presented as some sort of inspiration for American patriots. I do not know whether it is true that Putin money and cyber-technology are helping the Trump campaign. If not, and Mr Trump is doing the Russian leader's work for free, he is an even more peculiar customer than he seems. His threat this week to contest the democratic result would make any oligarch proud.
The West has no policy towards Russia, beyond protest at Putin's actions. It cannot have a policy without a strategy, and that strategy cannot be normalisation. It should be more like the old policy of "containment", not seeking to change Russia within, but setting limits to her ambitions by protecting our friends and allies.
One of the few things that has always worried me about Britain leaving the EU is the fear it will help Putin get what he wants. I do not believe that it will do so, however, because the EU cannot stop him anyway. It is ill-suited to conducting a great-power foreign policy which can link the military and political dimensions. The Cold-War experience, which we are being forced to revisit, tells us that this is best done by a strong Nato.
Now that Mrs May has become a Leaver, she would be a fine spokesman to press this thought upon the next president of the US.