Moscow(CNN) It was an impressive display of military might. The heaths of the Tsugol training range were transformed into a simulated battlefield, as a Russian and Chinese "coalition" fought a fictional adversary.
While Russian President Vladimir Putin watched, modernized Russian T-90 main battle tanks rumbled into position, staging an assault with the support of Chinese Type 99 tanks. An air strike featuring Su-35 fighter jets, a cornerstone of Russian-Chinese military interoperability, then followed.
Thursday's maneuvers were the capstone of Vostok 2018 -- the military exercises that Russia has billed as the largest it has staged since Cold War-era drills in 1981.
Russia holds large military exercises at this time every year. But this week's exercise was something different. It was an advertisement for a burgeoning military partnership between Moscow and Beijing, as well as a less than subtle pitch for exporting Russia's top-of-the-line military hardware.
Twenty-five thousand troops and 7,000 pieces of hardware were part of the Tsugol exercise on Thursday. And that was just a fraction of the total military strength that was mobilized for Vostok 2018.
The Russian Defense Ministry claimed some 300,000 soldiers were involved in all stages of the drills, which would make for almost a third of the entire active contingent of the Russian armed forces -- although some analysts questioned the overall numbers.
In a parade that followed the event, Putin said the drills underscored that Russia was "a peace loving country" that was equally poised to defend itself.
"Our duty to our country, our Motherland, is to be ready to defend its sovereignty, security and national interests of our country, and if necessary - to support our allies," he said, in an address to military attaches.
"That's why, we will continue to strengthen our armed forces, equip them with weapons and technology of the newest generations, and develop international military cooperation."
International cooperation -- specifically with China -- was the main feature of this year's air, sea and land exercises. Last year's exercise, Zapad 2017, focused on Russia's western frontier with NATO.
Zapad 2017 caused considerable concern in Western capitals, where it was seen as a deliberate counter to NATO's stepped-up military presence in the Baltics.
A NATO analysis after the exercises concluded that Zapad 2017 was meant to send a clear strategic signal.
"The character, scale and intensity of Russian military exercise activities during September 2017 is consistent with the system of strategic operations that Russia would conduct in conflict with NATO, focusing on the Western Strategic Direction, with supporting military activity nationwide in all strategic directions, and potential global operations, in an escalating conflict," the analysis stated. "If ZAPAD 2017 were actually conducted in line with its official description, it would exercise just a portion of Moscow's strategic plans for potential war with NATO."
The adversary that was vanquished by the Russian, Chinese and Mongolian coalition was not publicly characterized by the Russians as a stand-in for the US or its allies.
But the most striking thing was the sight of Russian and Chinese forces operating jointly in a region not far from where China and the USSR fought a real border war in 1969.
Times have changed. And while Moscow and Beijing remain strategic rivals in some respects, Putin has a warm relationship with Chinese President Xi Jinping. And Russia and China have been quietly stepping up military cooperation in recent years, even as relations between Moscow and the West entered a deep freeze.
"Vostok drills are aimed at countering foreign invasions and addressing military threats for Siberia and the Far East," said Alexander Gabuev, an expert on Russia-China relations at the Carnegie Moscow Center, in an analysis posted ahead of the exercises. "China was among potential adversaries for many years. Now Moscow's message is that it doesn't view Beijing as an adversary any more."
Gabuev noted that China had already taken part in numerous in a number of joint drills with Russia, including naval drills and missile-defense simulations. But many of the systems that were put through their paces -- including the S-300 and S-400 air-defense systems -- are weapons that Russia has exported to China.
US officials have expressed concerns that systems such as the S-400 could pose a threat to US and NATO military assets.
Despite frosty Russian relations with the West, Moscow's military officials were careful with the language ahead of the drills, saying there "is nothing unusual" about Vostok 2018 and that these had been planned long in advance to keep Russian military units in shape.
And China wants to learn military lessons from Russia. Far away from the exercise in eastern Russia, Moscow is engaged in a real-world conflict in Syria, where its air power and limited numbers of ground troops have backed the forces of Syrian President Bashar al-Assad.
"The Russian Army has a very vast experience in conducting practical combat operations and powerful combat capability," Maj. Gen. Shao Yuanming, deputy chief of the Joint Staff Department of China's Central Military Commission, told journalists after the main stage of the drills. "And for us it's been very useful to learn from the Russian army and get this very valuable experience."