It is a peculiar moment when, after an inquiry suggests President Putin’s “probable” part in the assassination of Alexander Litvinenko, the Leader of the Opposition, Jeremy Corbyn, says nothing, apparently being more sympathetic to the Kremlin than he is to a British government defending the right of a British citizen not to be murdered on the streets of London. What is behind this Corbynist conundrum?

In today’s perilous world, the rise of Corbyn on the Left is no more surprising than the rise of Donald Trump on the Right or that of, say, Beppe Grillo, the comedian who leads Italy’s second biggest party. Bewildered by all this, most mainstream commentators still treat Corbyn as a cuddly curiosity of childlike naivety while screaming with alarm at Trump’s advance. We are more tolerant of the Left. Of course foreign policy matters less in opposition and Corbyn’s quaint appeal is a domestic protest against conventional politics. But increasingly his foreign policies will blow back into the domestic sphere.

As Corbyn tightens control over Labour, the strangest thing about Corbynism is the inconsistency between the socialist pacifism at home and the anti-Western militarism abroad. At first his views seemed so colourfully crankish that they were hard to take seriously. As has been exposed since he became leader, Corbyn and his entourage have backed a motley crew of dictatorships and terrorist organisations, from the IRA in the Eighties to Hamas and Hezbollah (“our friends”), and have attended meetings with an array of sinister anti-Semitic conspiracists. (Corbyn makes clear he is not anti-Semitic himself.)

If you exclude the anti-Zionism, you might be forgiven for believing this is all history: in fact, it is about the present.

Corbyn’s entourage have a world view that is entirely different from that of virtually all Western governments. Their villain is “imperalist” America followed by Britain as colonial-oppressor-turned-American-poodle, joint perpetrators of the criminal Iraq war, while their preference is for the regimes/movements that oppose Western power.

Tyrants and terrorists are excused their brutalities because the Corbyn camp has an irrational faith in anyone who is anti-Western, no matter how mercilessly murderous or financially corrupt. To arm ourselves with nuclear weapons or drones to defend democracy is simply wrong. We do not need arms because, unlike Hezbollah, Iran, North Korea or China, we are incapable of using them for any purpose other than greed, slaughter and conquest.

You might expect these secular socialists to loathe Islamicists as medieval fanatics but they analyse jihadist terrorism as a reaction to Western crimes, believing the West must be guilty to arouse such hatred, an analysis of terrorist courage implied by Ken Livingstone when he said “because of our invasion of Iraq … they gave their lives”. Corbyn disapproved of drone strikes against IS and, after the Paris atrocities, of police shooting terrorists.

And then there’s Russia, which has a special place in this world view as the first Marxist state and vanquisher of Hitler. President Putin isn’t ideological; if anything he is a nationalist autocrat with a mission to restore Romanov-cum-Soviet authority, but that doesn’t matter because he opposes the US.

Seumas Milne, Jeremy Corbyn’s head of communications, has appeared on the propaganda channel RT to defend Russia’s Ukrainian adventures, for which he blamed Nato, and humbly interviewed Putin at a Kremlin-run conference. For years he has defended Stalinism in his Guardian columns: “For all its brutalities … communism in the USSR delivered rapid industrialisation, mass education, job security” and “if Lenin and Stalin are regarded as having killed those who died of hunger in famines of the Twenties and Thirties then Churchill is ... responsible for the four million deaths in the avoidable Bengal famine.”

At the weekend, Ken Livingstone defended not just Stalin’s part in the Cold War and Putin’s meddling in ex-Soviet republics with ethnic Russian populations, but seemed to excuse Litvinenko’s murder because “American presidents authorised assassination attempts against Castro”.

'Tyrants and terrorists are excused their brutalities because the Corbyn camp has an irrational faith in anyone who is anti-Western' Simon Sebag Montefiore

This Kremlin soft spot leads to one of Corbyn’s gaping inconsistencies: the unilateralist “pacifist” reluctant to shoot terrorists threatening to slaughter English civilians says nothing about the murder of Litvinenko.

Meanwhile, the sage promising honesty presides over a faction imposing its will on the Labour Party with Leninist ruthlessness.

Last week, Labour grandee Lord Soley attacked Corbynists for being “always overly sympathetic to authoritarian regimes and under-sympathetic to countries that enjoyed democracy”. When Livingstone said “I wish Obama was as effective a leader as Putin”, he gave the game away. Corbyn’s faction disdain the collegial compromises and quest for centrist consensus that safeguard the freedoms of democracies, unavailable in, say, Hamas-ruled Gaza. They admire Putin, who can order actions that would take a Western leader years of compromise and negotiation.

In his essay The Lion and the Unicorn: Socialism and the English Genius, George Orwell described “the power worship which has infected the English intelligentsia”, adding that an English socialist “would feel more ashamed of standing to attention during God Save the King than of stealing from a poor box… Many Left-wingers were chipping away at English morale, trying to spread an outlook that was sometimes squashily pacifist, sometimes violently pro-Russian, always anti-British”.

As Orwell foresaw, Corbyn’s “pacifists” are worshippers of the glamour of that species of supreme power that only comes from the deployment of violence to change society. Orwell insisted British voters would never buy this: “Power-worship has never touched the common people.” But it didn’t matter much then because these were the views of factions on the borderlands of politics. Now they do matter; this puzzling farrago forms the views of the Opposition. Even if Corbyn is unelectable, they have never been closer to power than they are today.

The Romanovs, 1613-1918, by Simon Sebag Montefiore, is out this week.