Xi, who met with Russian President Vladimir Putin during the trip, told Russian media that relations between the two countries were currently at their "best time in history." The Chinese president also said Russia and China were each other's "most trustworthy strategic partners," Xinhua reported.

Strategic ties between Russia and China were appraised in glowing terms as Chinese President Xi Jinping wrapped up a two-day state visit to Russia, concluding with at least $10 billion in agreements.

Russian President Vladimir Putin (R) shakes hands with his Chinese counterpart Xi Jinping during a signing ceremony following the talks at the Kremlin in Moscow, Russia July 4, 2017.

"China-Russia relations do appear to be smooth right now, but relations between those two major power neighbors have had a long history of ups and downs," said Ja Ian Chong, an associate professor at the National University of Singapore, adding that changes in the nature of that relationship can be sudden and dramatic.

One impetus for the ramp up in diplomatic cooperation could be developments in U.S. foreign policy.

"The fact that the U.S. seems far less systematic in its foreign policy than in the past creates space for China and Russia to make the best of the situation," Chong told CNBC.

Hugo Brennan, Asia analyst at Verisk Maplecroft, added that President Donald Trump's approach to foreign policy was more likely to foster alignment between Beijing and Moscow than it was to thrust a wedge between the two.

Aside from the reiteration of closer strategic ties between the states, other issues discussed during Xi's visit included the deepening of economic linkages and security concerns.

Although details about the exact nature of the proposed enhancements in trade and investment remained unclear, an investment fund worth $10 billion was announced during the trip, the Financial Times reported.

Signed into agreement on Tuesday, funds from the Russia-China RMB Cooperation Fund are expected to be invested in infrastructure projects linked to China's "One Belt, One Road" (OBOR) initiative and the Eurasian Economic Union ー a trading bloc championed by Putin. Russian state media said the investment fund was an agreement between the Russian Direct Investment Fund sovereign wealth fund and the China Development Bank.