There is only one man on Earth who holds sway over Vladimir Putin, the rogue, isolated president of the Russian Federation who has fractured Europe in a way not seen since Adolf Hitler attacked Poland on September 1, 1939, after the Nazi annexation of Austria and the Sudetenland the previous year.

That man is Xi Jinping, president of the People’s Republic of China and secretary general of the Chinese Communist Party. On February 4 in a joint statement, Putin and Xi announced that their friendship would have “no limits.”

Earlier this week, Chinese Foreign Minister Wang Yi signaled China’s willingness to mediate in the Ukraine crisis. And on Tuesday Xi himself stated that China would participate in mediating the conflict.

Time is running out. Thus far Putin has not been deterred by brutal sanctions such as kicking Russian banks out of SWIFT, freezing the central bank’s $630 billion in foreign currency reserves, the exiting of blue-chip multinationals, suspending the Nord Stream 2 natural gas pipeline by Germany, and seizing the personal property of oligarchs who owe their status and privilege to the Russian president. Even relatively neutral countries — Finland, Sweden, and Switzerland — have taken action by sending weapons or endorsing sanctions.

Putin’s raging inferiority complex and obsession with restoring the glory of the Soviet if not Czarist Empire will, if unchecked, result in the further leveling of Ukrainian cities not seen since the devastating allied bombardments of Germany in World War II, and a subsequent guerrilla war against the occupational Russian army. The will of the Ukrainian people and the heroic persona of President Volodymyr Zelensky have already reminded a complacent West that freedom has its price. Armed with American-made surface-to-air Stingers and Javelin anti-tank fire-and-forget, shoulder-fired weapons, and inspired by President Zelensky, the Ukrainian resistance can inflict substantial losses for some time to come, increasing the cost of Putin’s war. (READ MORE from Frank Schell: Ukraine: India’s Balancing Act)

The civilized world wonders how this catastrophe will end. If the Russian military continues to underperform, more doubts about its competence arise, and President Putin becomes more and more isolated at his oversized, ornate white table, he still has the tactical nuclear weapon in his playbook. Its use on a Ukrainian city would horrify the world and probably stop the Ukrainian resistance. It could also demand a more aggressive response by the U.S. and NATO. This possibility makes China’s offer even more important, and potentially useful.

The irony of Chinese cavalry coming to the rescue is indeed profound. Nonetheless, China and Russia have forged ever-closer bonds in recent months, the aim being to end the U.S.-dominated postwar order for trade, investment, and diplomacy. While Chinese mediation will legitimize and enhance China’s posture on the world stage, it will carry with it a price. So what must the West give China, in the catbird seat, for its ostensibly good behavior? The solution will fall upon the United States, China’s chief rival. Britain and France can support but they cannot lead, and Germany is busy repudiating years of the pro-Putin policy of the Christian Democratic Union.

China’s continued anger over U.S. support of Taiwan, which it views as a renegade province, is nonstop and predictable. Since 2010, the U.S. arms sales to Taiwan total $23 billion. As recently as early February, the U.S. announced a $100 million aid package to upgrade Taiwan’s Patriot missile system to protect against airborne threats. U.S. support for Taiwan’s independence and military are the single most important issue to Xi Jinping — who could demand cessation of military support by the United States.

Other demands that China could make are more diplomatic and optical in nature, to enhance China’s image in the West. Moderation of anti-China rhetoric with regard to human rights violations in Hong Kong and repression of Uyghurs, a Turkic ethnic population in western China, would be on the table. China could also demand that the West back off on correctly holding them responsible for a Chinese cover-up of COVID-19 for months preceding lockdowns in the West. China could also ask that the U.S. accept the militarization of the South China Sea and cease airborne and naval reconnaissance patrols. Xi might also ask the U.S. to remove existing tariffs and sanctions.

It has been speculated that a coup d’état in Russia or national revolt by the Russian people could oust Putin. Both would probably require the sanctions to continue to bite deeply, and that will take more time.

The West is not in an enviable position. Which is worse: Allowing China to preen, grandstand, and appear benevolent, giving in to some Chinese demands — or letting an unhinged Vladimir Putin continue to sink and rage, with his finger not far from the trigger of Armageddon?

Xi Jinping does not have to read this opinion piece to know that he now has the potential leverage with the West that he has dreamed of for years.

Frank Schell is a business strategy consultant and former senior vice president of the First National Bank of Chicago. He was a Lecturer at the Harris School of Public Policy, University of Chicago and is a contributor of opinion pieces to various journals.