By Nectar Gan, Shawn Deng and Philip Wang, CNNUpdated 0728 GMT (1528 HKT) September 12, 2022

Russian President Vladimir Putin, center, Chairman of National People's Congress Li Zhanshu, left, attend a plenary session at the Eastern Economic Forum in Vladivostok, Russia.

Hong Kong (CNN)As Russian forces suffer a string of stunning defeats in Ukraine, Moscow is playing up Beijing's support for its invasion ahead of a key meeting between Russian President Vladimir Putin and Chinese leader Xi Jinping this week.Russian troops were forced to flee the strategic city of Izium -- their main bastion in northeastern Ukraine -- on Saturday after a swift Ukrainian counteroffensive.It was Moscow's worst defeat since its retreat from Kyiv in March -- and a sign that the war might be entering a new phase. Over the past week, Ukrainian forces have recaptured more than 3,000 square kilometers of territory -- more than Russian forces have captured in all their operations since April.Warner explains what's driving Ukraine's gains against Russia 01:38Back in Russia, senior Russian and Chinese officials put on a united front to pave the way for an expected meeting between Putin and Xi on the sidelines of a regional summit in Uzbekistan -- their first face-to-face meeting since Russia's invasion of Ukraine.And according to the Russian Parliament, a senior Chinese leader has voiced explicit support for Russia's war on Ukraine -- claims that are not included in the statement from the Chinese side, and run contrary to Beijing's previous efforts to maintain a veneer of neutrality.