Putin will travel to China this week to meet Xi Jinping, the Kremlin chief's first trip outside the former Soviet Union this year.
What are the five things to watch for at the meeting?
As Defence Minister Li Shangfu has not been seen in public for more than six weeks, China watchers will be looking at who takes the lead in any talks with Russian military officials on cooperation.
Li was sanctioned by the U.S. in 2018 for an arms deal he secured with Russia in an earlier role. General Liu Zhenli, the head of the military body responsible for China's combat operations and planning, has emerged as the top contender for the job.
For China, Russia is a not only a major source of oil and gas: the world's biggest nuclear power is also a rich potential source of technology as the People's Liberation Army (PLA) seeks to modernise its conventional and nuclear forces by 2035.
Russian aviation, rocket and even submarine technology has been shared over recent decades with China, according to a 2022 assessment by the U.S. Department of Defence.
China and Russia closely cooperate on civilian nuclear plants — some of which could be used to produce military grade plutonium, such as the fast breeder rectors at Xiapu.
China has refrained from condemning Russia's operation against Ukraine or calling it an «invasion» in line with the Kremlin which casts the war as «a special military operation».
The United States has warned China against sending any weapons to Russia, though China is the second largest importer of Russian crude after India and thus supports Russia's economy.
China has denied reports in Western newspapers that it has sent weapons to Russia.
BEST FRIENDS?
Both Putin and Xi like to