When President Xi Jinping met his Russian counterpart Vladimir Putin at the Asia-Pacific Economic Co-operation (Apec) leaders meeting in Bali this week, both greeted each other like old friends.
"This is the fifth meeting we had during the year and it is strong evidence of the high level and uniqueness of China-Russia relations," Xi was quoted by Xinhua as telling Putin.
Just five weeks ago, Xi met Putin in St Petersburg at the G20 summit, during which China and Russia opposed a US proposal for military intervention in Syria after UN chemical weapons inspectors confirmed that hundreds of civilians were killed by the nerve gas sarin near the capital, Damascus, on August 21.
Analysts said Beijing and Moscow were seeing eye to eye more than they have in decades as the two former foes found common ground in areas ranging from economic co-operation to international security to military technology transfers.
The cozying up of the two giant neighbours comes against Washington's diplomatic and military pivot to Asia as well as growing tension between the US and Russia over such issues as Syria and Moscow's granting of asylum to the whistle-blowing former National Security Agency contractor, Edward Snowden.
Tian Chunsheng , an analyst at the Russian Development Research Centre of the State Council, said Xi and Putin realised they had further common strategic interests after Washington's efforts to establish its Trans-Pacific Partnership Agreement (TPP) and Transatlantic Trade and Investment Partnership (TTIP) during the past two years.
The TPP is a free-trade deal being negotiated by 12 countries: the US, Japan, Canada, Mexico, Australia, New Zealand, Peru, Chile, Vietnam, Malaysia, Singapore and Brunei, but China has not been invited.
The TTIP is a trade and investment agreement being negotiated by the US and the European Union.
"Both the TPP and TIPP have deliberately or unwittingly ignored China's interests, or may be aimed at limiting China's rise, which has forced Beijing to seek a more appropriate [strategic] global partner. Russia is the ideal candidate," Tian said.
"Indeed, Xi and Putin are keen to boost co-operation in emerging industries in the Asia-Pacific region because economic growth has slowed in both countries since the global financial crisis."
She added that Russia's new strategy to expand its political and economic influence in East Asia coincided with China's plan to strengthen its leading role in the region as a foil to Washington's renewed focus on Asia.
Xing Guangcheng , a specialist on Russian affairs at the Chinese Academy of Social Sciences, played down America's influence on political and military ties between China and Russia.
"Beijing and Moscow realise that the US has never left Asia ... The new Sino-Russia leadership under Xi and Putin has merely inherited the legacies of their predecessors, including Jiang Zemin , Hu Jintao , Dmitry Medvedev and Boris Yeltsin," Xing said.
"The two countries realise that, as neighbours, they should be friendly. The alternative could be a disaster for both. They know this having suffered many ups and downs in the relationship over past centuries."
Xing said he believed that the two countries' strategic partnership had remained unchanged despite the collapse of the former Soviet Union in 1991.
The two countries conducted joint military drills in July, and there was much room for other collaboration, Xing noted.
"Russia is an energy superpower; China is energy-hungry," he said. "Russia is a huge country that also needs China's help to perfect its infrastructure."