Vladimir Putin’s ongoing failure in Ukraine has put his strategic alliance with Chinese President Xi Jinping to the test.

With Putin growing ever more desperate, Xi must finally realize the scale of the threat that his “friendship without limits” with the Russian president poses to China’s economic health, to global stability and to his own geopolitical ambitions.

While Putin may or may not have been bluffing when he threatened to use tactical nuclear weapons in Ukraine last month, Xi must assume the worst if he wants to be viewed as a responsible leader. After all, Russia’s military doctrine allows for a nuclear strike to defend Russian territory against an existential threat. Russia’s illegal annexation of the occupied Ukrainian regions of Luhansk, Donetsk, Kherson and Zaporizhzhia provides the pretext for such an attack.