Xi personally warned Putin against launching a nuclear strike in Ukraine, report says, drawing a red line for Russia

• China's Xi Jinping warned Vladimir Putin against using nuclear weapons, The Financial Times reported.
• It underscores the new influence Xi has with Putin, amid Russia's isolation over Ukraine.

At March's Moscow summit, President Vladimir Putin of Russia and China's Xi Jinping toasted their nations' enduring alliance and bonded over their shared opposition to US global power.

But behind the facade, key differences remained between the leaders, the Financial Times reported.

According to the outlet, citing Chinese and Western diplomatic officials, Xi personally warned Putin against following through on his threats to launch a nuclear strike against Ukraine.

If true, the extraordinary intervention shows that Xi has placed clear limits on the extent to which he's willing to back Russia's president.

A red line for Xi

For months, Putin had been escalating his menacing rhetoric towards Ukraine and its Western allies with the prospect of a nuclear attack.

But the use of nuclear weapons appears to be a red line for Xi in his support for Putin, and the Chinese president is using his new influence in Moscow to enforce it.

The Kremlin on Wednesday denied the Financial Times report. Putin's spokesperson, Dmitry Peskov, told reporters the two countries had given statements at the time on the content of their talks, and said all other reports about Xi's state visit to Moscow were "fiction".

"If even mildly true, shows how the relationship has changed and who is the real power in the East," tweeted Sumantra Maitra, a journalist and national security scholar, of the report.

Xi is one of few leaders of a major power to have backed Putin over the Ukraine invasion.

He has provided the Russian president with crucial economic and diplomatic support amid sanctions and international isolation. This gives him leverage over the Russian president in seeking to deter him from a potentially catastrophic escalation of the conflict.

A balancing act for China

Xi is performing a balancing act in his stance on Ukraine. He want a Russian victory in Ukraine to humiliate the US, yet doesn't want to anger European countries whose economies China remains dependent on and which would be in the front line of the fallout from a Russian nuclear attack.

"A Russian use of tactical nuclear weapons would severely undermine China's efforts to stabilize relations with the European Union," Ali Wyne, an analyst with the Eurasia Group, told Insider.

"Paradoxically, it would also increase the likelihood of an outcome that China hopes to avoid—a Russian battlefield defeat—by accelerating NATO's provision of advanced weaponry to Ukraine and encouraging the alliance to strike Russian forces."

"Finally, it would be an embarrassing rebuke to Xi Jinping, who has not only publicly stated China's opposition to using nuclear weapons in the war, but also, it appears, personally warned Vladimir Putin against taking that fateful step."

Yet Putin's previously unchallenged power in Russia is under threat as never before. On June 28, mercenaries from the Wagner group staged a mutiny against Russian military leaders, in a move likely to have rattled officials in Beijing.

Ukraine is seeking to exploit the chaos, doubling down on an offensive aimed at driving Russian forces back from the territory they occupy.

Analysts have previously told Insider that Putin could decide to escalate the conflict if there is a serious chance of defeat in Ukraine, and his grip on power is further weakened, with the use of tactical nuclear weapons among the options available.

Putin has previously shown a willingness to defy China, declaring he'd position nuclear weapons in Belarus in an apparent snub to Xi in March.

If there are further serious setbacks for Putin, Xi could find himself in the unenviable position of trying to talk down the Russian leader from the nuclear brink.

"China seeks to deepen its relationship with Russia while conveying to the West that Beijing can and will dissuade Moscow from moving the war into a far more dangerous, unpredictable stage," said Wyne, of China's likely strategy.