Hundreds of thousands Russian troops have swept across Siberia in the nation's largest ever war games also joined by China - a powerful show of burgeoning military ties between Moscow and Beijing amid their tensions with the US.
Moscow said the weeklong Vostok (East) 2018 manoeuvres will span vast expanses of Siberia and the Far East, the Arctic and the Pacific Oceans and involve nearly 300,000 Russian troops - nearly one-third of the country's one-million-strong military. They will feature more than 1,000 aircraft, about 36,000 tanks and other military vehicles and 80 warships.
Russian Defence Minister Sergei Shoigu has described the drills as even bigger than the country's largest Cold War-era exercise called Zapad 1981 that put NATO allies on edge.
A retired Russian general said that the giant war games come as a warning to the US against ramping up pressure on Russia.
"The manoeuvres are aimed at deterring the aggressive intentions of the US and NATO," Retired General Leonid Ivashov said. He was quoted by the Interfax news agency as saying that the drills are "also a response to the US sanctions."
China is sending about 3,200 troops, 900 combat vehicles and 30 aircraft to join the drills at a Siberian firing range, a significant deployment that reflects its shift toward a full-fledged military alliance with Russia. Mongolia also has sent a military contingent.
Asked if the US is worried about a possible military alliance between Russia and China, Defence Secretary Jim Mattis told Pentagon reporters on Tuesday that, "I think that nations act out of their interests. I see little in the long term that aligns Russia and China."
As the manoeuvres kicked off, Chinese President Xi Jinping visited Russia on Tuesday to attend an economic forum in Vladivostok.
President Vladimir Putin treated Xi to pancakes with caviar and shots of vodka in a show of their warm rapport.
Moscow and Beijing have forged what they described as a "strategic partnership," expressing their shared opposition to the "unipolar" world, the term they use to describe perceived US global domination. However, the military drills they had until now were far smaller in scale, reflecting China's caution about alliances.
Some experts pointed out that the US helped spawn closer Russia-China military ties by labelling them strategic competitors.
"They feel they need to embrace to deal with the increasingly high pressure and containment from the US," said Yue Gang, a military expert and retired Chinese army colonel.
He noted that China feels that the Washington's hostile attitude and actions, such as deploying the THAAD missile defense system in South Korea, relieve it of any need to take US views into consideration when deepening strategic trust with Moscow.
"The war games have laid a foundation for China and Russia to enhance cooperation on international arena and will lift the combat proficiency of both sides," he said.
The Chinese media touted the Chinese involvement in the manoeuvres as the country's largest-ever dispatch of forces abroad for war games.
Some noted that the People's Liberation Army, which hasn't fought a war since the attempted invasion of Vietnam in 1979, is keen to learn from Russia's experience in the Syrian campaign, where it tested its latest weapons and tactics.