CHITA, Russia (AP) -- Hundreds of thousands Russian troops swept across Siberia on Tuesday 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 U.S.
Moscow said the weeklong Vostok (East) 2018 maneuvers 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 1-million-strong military. They will feature more than 1,000 aircraft, about 36,000 tanks and other military vehicles and 80 warships.
Russian Defense 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 U.S. against ramping up pressure on Russia.
"The maneuvers are aimed at deterring the aggressive intentions of the U.S. and NATO," Ret. Gen. Leonid Ivashov said. He was quoted by the Interfax news agency as saying that the drills are "also a response to the U.S. 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 U.S. is worried about a possible military alliance between Russia and China, Defense Secretary Jim Mattis told Pentagon reporters 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 maneuvers 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 U.S. 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 U.S. helped spawn closer Russia-China military ties by labeling them strategic competitors.
"They feel they need to embrace to deal with the increasingly high pressure and containment from the U.S.," 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 U.S. 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 maneuvers 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.
From China's perspective, the emerging military alliance with Russia sends a strong signal to the U.S. and its ally Japan as Beijing moves to defend its interests in the South China Sea, which China claims virtually in its entirety, as well as Taiwan and the Senkaku and Diaoyu islands controlled by Japan but claimed by Beijing.
Hong Kong-based commentator Song Zhongping said China is anxious to acquire more experience in large-scale operations that might become a factor in a conflict with the U.S. and others over territorial claims in Asia.
"Russia has very strong real combat abilities and the participation of the PLA in such a large-scale military exercise that is specially tailored for an anti-invasion war indicates China's intention to learn more valuable combat practices and lift its ability for joint combat," Song said.
For Russia, the increasingly robust alliance with China is particularly important amid the growing tensions with the U.S. and its allies and a looming threat of more biting U.S. sanctions.
"The scale and the scenario of those drills are in line with the current military-political situation," said Ivashov, the retired Russian general. "They demonstrate the seriousness of our intentions."
The U.S. and its NATO allies are closely eyeing the exercises for what they reveal about military cooperation between Russia and China and their mounting military might.
"We're obviously aware of it, we're watching it closely," said Army Col. Rob Manning, a Pentagon spokesman. "We're aware of Russia's right to sovereignty and to exercise in order to ensure their readiness."
NATO Spokeswoman Oana Lungescu said that the training "fits into a pattern we have seen over some time: a more assertive Russia, significantly increasing its defense budget and its military presence."
She also noted that "China has growing military capabilities and is playing an increasingly significant global role," adding that "it's important for NATO to engage with China."