Let’s all hope that Chinese president Xi Jinping sees this outrage as a personal affront and gives his “friend” in Moscow a good talking-to at once.

Only days ago, Xi was paying Russian president Vladimir Putin a visit — to discuss their collaboration, but also to talk him out of nuclear escalation and into a peace process with Kyiv. This weekend, Putin did the exact opposite.

In perhaps the most insidious of his many nuclear threats against Ukraine and the West, Putin announced that he would station tactical nukes in Belarus, his fellow dictatorship and vassal state just to the west. From there, even missiles and jets with shortish ranges could strike targets in Ukraine or Central Europe.

Disingenuously as ever, Putin claims that this move will not breach Russia’s obligations under the Treaty on the Non-Proliferation of Nuclear Weapons. His logic is that he, rather than Belarusian dictator Alexander Lukashenko, would retain control over the warheads and the missiles that would carry them. That makes it all right, apparently.

In reality, Putin is once again ignoring — or perhaps relishing — the bitter irony of the perfidious path he followed to this moment in history. In the so-called Budapest Memorandum of 1994, both Ukraine and Belarus — as well as the third former Soviet republic then in possession of nukes, Kazakhstan — agreed to surrender their atomic arsenals in return for security guarantees from Moscow.

So much for Russian security guarantees. These days, Putin claims Ukraine is not a nation at all, and must be subjugated or destroyed. And he regards Belarus as a personal fief destined eventually to be merged into a “Union State” with, obviously, Putin at its head.

The lesson for wannabe tyrants and aggressors everywhere — from North Korea to Iran and beyond — is plain. Only nukes can offer them insurance against nuclear blackmail from ruthless aggressors such as Putin, and can simultaneously serve as instruments of extortion in their own toolkits. Yes, Putin has just launched a new era of proliferation.

His escalation is especially odious because it rhymes with his suspension last month of New Start, the only remaining arms-control treaty to limit strategic nukes. (Tactical warheads, which can have relatively “small” yields, are intended for use on the front to win battles, whereas strategic nukes are designed for deployment against the enemy’s homeland as a means of apocalyptic deterrence.)

As ever, Putin is using the full repertoire of the KGB methods he learnt in his early career, distorting reality to create narratives that Russians and “useful idiots” in other countries will spread. Sending nukes to Belarus is only a proportionate answer to British plans to give Ukraine shells made of depleted uranium, he suggests. But the depleted uranium cannot cause fission, and shells containing it are not nuclear weapons.

Putin is also trying to conflate his own plans in Belarus with the longstanding American practice of stationing nuclear bombs in Allied nations such as Belgium, the Netherlands, Germany, Italy and Turkey. But those arsenals — whatever their merits at the time — date to the Cold War. Neither Washington nor any other capital in control of nuclear weapons would dream of placing such warheads closer to Russia in the present state of tension.

So Ukraine is right to call an immediate session of the United Nations Security Council. Russia has a seat on it, but so does China, which should use its new clout with Putin to talk him out of this madness. Better yet, Xi should pick up the phone right now and remind Putin just where their friendship ends.

And Belarusians — including the top brass of the army — should contemplate agitating against their dictator once again, to stop Putin from dragging them into disaster with him.

Ukraine and the West, meanwhile, must not let Putin spook them into hysteria. The Russian president has become so unpredictable and reckless, so deranged in his view of the world and his own destiny in it, that only steely resolve and calm strength can deter him from making a bad situation immeasurably worse.

• Andreas Kluth is a Bloomberg Opinion columnist covering European politics. A former editor-in-chief of Handelsblatt Global and a writer for The Economist, he is author of Hannibal and Me