Russian President Vladimir Putin and his Chinese counterpart Xi Jinping have reaffirmed their alliance ahead of a change of the US government in January.
The Russian presidential office announced a telephone conversation between the two leaders on Monday.
The office said that "the leaders praised bilateral ties, stating that they have reached the highest level in history and are truly beneficial to both sides."
It added the presidents reaffirmed their shared willingness to step up cooperation in the international arena.
China's foreign ministry quoted Xi as saying the strategic cooperation between China and Russia can effectively resist any attempts to suppress and divide the two countries.
The militaries of China and Russia conducted joint surveillance operations by strategic bombers over the Sea of Japan and the East China Sea on December 22.
Monday's summit talks over the phone are seen as an attempt to reinforce the bilateral ties before US President-elect Joe Biden is inaugurated next month.
Biden is expected to take hardline policies against Russia and China.