Military ties between China and Russia appear to have taken a leap forward after Russian President Vladimir Putin said his country is helping Beijing build a system to warn against ballistic missile launches.
Speaking at the Valdai Club international affairs conference in Sochi on Thursday, Putin confirmed the move, adding that it would promote China to a level of defense only currently enjoyed by Russia and the U.S.
"This is a very serious thing that will dramatically increase China's defense capability because only the U.S. and Russia have such a system now," Putin said.
Global Forecasting Director at The Economist Intelligence Unit, Agathe Demarais, told CNBC via email Friday that such a system is viewed as "a crucial part of modern nuclear deterrence."
Details of the size and make-up of the missile defense system that Russia will build for China is unknown. At present China employs limited resources which includes a small Russian S-300 system which considered only a modest deterrent against cruise and ballistic missiles.
Russia's existing S-400 is claimed to be capable of intercepting ballistic missiles with a range of 3,500 km. That program was controversially sold to NATO-member Turkey this year, much to the displeasure of Washington.
In recent months, Russia and China appear to be increasing their economic, political and military ties. Chinese President Xi Jinping even went so far as to call Putin his "best friend" during a state visit to Russia this summer.
Demarais said as well as representing a willingness to work with each other Putin and Xi's defense deal also shines a spotlight on fractious relations between Washington and Moscow.
"This statement highlights Russia's growing defiance towards the U.S. and Moscow's willingness to build ties with Beijing, which raises alarm bells in the U.S.," said Demarais.
In September, Russian and Chinese news agencies reported that the two countries want to double their trade over the next five years to a value of $200 billion.
Demarais cautioned that while there was recent public warmth between the strongman leaders, the economic relationship between China and Russia was not yet hugely significant.
"Russia's much-trumpeted pivot towards Asia is so far not taking place, with little energy supplied by Russia to Asian countries and low levels of Russian exports to China. Conversely, China does not appear to prioritize cementing its relationship with Russia, which it sees as a junior partner," Demarais said.
The EIU analyst said aside from military and defense tie-ups, two other areas of developing Russia-China relations are finance, where currency swaps help Russia avoid using the U.S. dollar; and nuclear energy, where Russian state-owned nuclear firms are to build power plants in China.