MOSCOW -- Russia caused a major stir earlier this month when it deployed one of its most advanced air defense systems, the S-300V4, on a disputed northern island claimed by Japan.
This was no isolated incident: For several years now, Moscow has been on a mission to strengthen its military presence in Northeast Asia. To counter the U.S., Russia has upgraded its weaponry in its Far East, commissioned new ships for its Pacific Fleet, and significantly expanded military cooperation with China.
The buildup adds another layer of complexity in a region often preoccupied with territorial friction in the South China Sea -- and presents a challenge to U.S. President-elect Joe Biden's incoming administration.
Russia says the S-300V4 went live Dec. 1 on Iturup -- known as Etorofu in Japan. The island is one of the four southern links in the Kuril Islands chain claimed by Tokyo, which refers to them as the Northern Territories. This puts sophisticated Russian missiles on the doorstep of Hokkaido, Japan's northernmost main island.
Tokyo quickly lodged an official protest and denounced the move as "unacceptable."
The deployment followed Russian Defense Minister Sergei Shoigu's announcement in September that troops in the Far East would receive over 500 units of "new and modernized equipment" before the end of the year.
"The military and political situation in the Eastern strategic direction remains tense," Shoigu said. "The Eastern Military District has come up with a set of measures to thwart the emerging threats. Military contingents in the most important directions are being consistently reinforced."
Since 2016, Russian forces in the Far East have received over 3,700 units of new weapons and military equipment, according to public data from Russia's Eastern Military District. This includes everything from missiles and artillery to fighter jets and tanks.
Likewise, in 2018, the Russian Defense Ministry pledged to bolster the country's Pacific Fleet with 70 new warships and support vessels by 2027. Despite an overall slowdown in production due to the coronavirus pandemic, the fleet is set to receive 15 new ships before the end of this year.
Russia is doing this with the U.S. and its Northeast Asian allies in mind, according to experts.
"If you look at the weapons systems deployed by the Russian Defense Ministry to the Far East in recent years, then you'll notice that these systems are meant to repel a threat from the sea and the air, not a land-based threat from China," said Artyom Lukin, a professor of international relations at Russia's Far Eastern Federal University.
"We are not preparing to repel a hypothetical Chinese invasion across the Amur River," he continued. "Instead, the emphasis in military planning in the Far East is aimed at containing the U.S.-Japanese threat."
The confrontation with the U.S is not purely theoretical. Russian and American forces have squared off in numerous tense encounters in the Sea of Okhotsk, the Bering Strait and the Sea of Japan in recent years. Each country has accused the other of conducting provocative naval and aircraft patrols near their borders.
Most recently, in late November, the U.S. Navy destroyer USS John S. McCain sailed 2 km into Peter the Great Gulf, a body of water near the major Russian port city of Vladivostok. Russia considers the gulf to be its territorial waters, but the U.S. does not recognize this claim.
Shortly after spotting the McCain, Russia's Pacific Fleet dispatched the Admiral Vinogradov destroyer to intercept and threaten to ram the American vessel unless it left the area. The McCain withdrew, the Russian Defense Ministry reported, although the U.S. denies that it was expelled.
Another source of tension between the two countries is a potential U.S. missile deployment in Asia. In August 2019, the U.S. pulled out of the Intermediate-Range Nuclear Forces Treaty with Russia, which banned any ground-launched cruise or ballistic missiles with ranges between 500 km and 5,500 km. Just days later, the Pentagon announced that it was looking to field such missiles in Asia. Japan is considered a leading candidate to host them.
The prospect of U.S. missiles near its eastern borders has pushed Russia's military leadership to put an even greater emphasis on Northeast Asia, experts say.
"Russia may be trying to stay ahead of a move by the United States to deploy missiles in Japan that have the potential to reach their territory," said Yoshinaga Hayashi, a retired major general in Japan's Air Self-Defense Force.
Hayashi added that Tokyo's interest in acquiring Washington's Aegis Ashore missile defense system aggravated Moscow's concerns. "The Aegis Ashore is a defensive system, but any missile can become an offensive weapon," he explained.
Japan scrapped plans to acquire the land-based system but recently said it intends to build two naval vessels equipped with Aegis interceptors instead.
In this climate, Russia has made a point of bolstering defenses on the Kurils. In recent years, it has deployed new coastal missile systems, radar stations, fighters, drones, tanks, and a machine-gun and artillery division. The military also established an airfield on the islands, and is reportedly working to create a naval basing point.
But the S-300V4 is easily the most advanced system deployed there so far. The S-300V4 is capable of firing hypersonic missiles and hitting targets at ranges up to 400 km and altitudes up to 37 km. It can also intercept up to 24 aerial targets simultaneously. And unlike older versions of the S-300, the S-300V4 is mobile, allowing it to provide coverage for troops on the move.
Alexey Lenkov, a military analyst for the influential Russian defense journal Arsenal of the Fatherland, told Nikkei Asia that by deploying the S-300V4, Russia hopes to turn the Kuril Islands into a "fortified area" and thwart potential threats from reaching the mainland.
"Russia is currently fulfilling its program of establishing a layered air defense system along the perimeter of its borders," Lenkov said. "The S-300V4 is one of the key components of that. It is a distant frontier system that targets ballistic missiles, cruise missiles and large aircraft such as strategic bombers and reconnaissance planes."
All of this is hard for Japan to swallow. The Kuril Islands belonged to Japan before World War II, but the Soviet Union occupied them during the final days of the conflict. Japan has never recognized Moscow's ownership, and decades of negotiations have failed to resolve the dispute.
Growing military coordination between Russia and China will not sit well with Japan and the U.S., either. Russian President Vladimir Putin himself said in late October that a military alliance with China is "quite possible."
Since 2012, Moscow and Beijing have conducted regular joint naval exercises in the Sea of Japan, Yellow Sea and East China Sea. In September 2018, thousands of Chinese troops and hundreds of tanks arrived in eastern Siberia to participate in Vostok 2018, Russia's largest military exercise since the Cold War.
Then, in July 2019, Russia and China held their first joint bomber patrol over the Sea of Japan. The patrol sparked protests from Japan and South Korea, which calls it the East Sea, and even prompted the latter to fire hundreds of warning shots.
Some are skeptical that the joint maneuvers and talk of an alliance are anything more than bluster. "Russia could challenge the U.S. by partnering with China, but I don't think there is a lot of support for such a partnership in Russia yet," Hayashi said.
But Lukin argued that Russian and Chinese naval forces in Northeast Asia are uniquely compatible: China has the world's largest navy, while Russia is bold and experienced enough to challenge the U.S. at sea.
"We could very well imagine a scenario where the two countries create a joint naval group in which China provides material resources and ships," he said, "and Russia's role consists in performing military operations that require audacity."
Additional reporting by Mitsuru Obe in Tokyo.