The rulers of the world’s largest nation – and its second largest economy – are not bothered by human rights violations, which Putin must find comforting. China, from Putin’s point of view, is the last global power to criticize him for his aggressive policies and assault on democracy. He needs such an ally for the sake to avoid being totally isolated.
The economic benefits are impressive also. China will pay as much as $400 billion for 30 years of gas supplies and substantial amount of this money comes up front, which makes Russia much less vulnerable to Western sanctions.
No European Union participation in the South Stream pipeline? Fine, Russia will have enough money to invest in it, at least at this point.