China is extending threatening military exercises around Taiwan that have already disrupted shipping and air traffic, further fuelling concerns about potential conflict in the region.
According to Moscow, the exercises include anti-submarine drills, apparently targeting US support for Taiwan in the event of a potential Chinese invasion.
The Chinese military has said the exercises involving missile strikes, warplanes and ship movements crossing the midline of the Taiwan Strait dividing the sides were a response to US House Speaker Nancy Pelosi's visit to the contested island last week.
In continued retaliation to Ms Pelosi's trip, China has imposed sanctions on her, and it has cut off defence and climate change talks with the US.
Beijing branded the visit as a "gross interference" in its internal affairs, while US Secretary of State Antony Blinken called the military response to the trip "flagrantly provocative".
China claims Taiwan as its own territory and has threatened to annex it by force if necessary. The two sides split in 1949 after a civil war, but Beijing considers visits to Taiwan by foreign officials as recognizing its sovereignty.
Taiwan's premier has condemned China as the "evil neighbour next door" after its military began live firing drills around the island.
China has ignored calls to calm the tensions, and there was no immediate indication when it would end what amounts to a blockade.
Taiwan's defence ministry said on Sunday it detected a total of 66 aircraft and 14 warships conducting the naval and air exercises.
The island has responded by putting its military on alert and deploying ships, planes, and other assets to monitor Chinese aircraft, ships, and drones that are "simulating attacks on the island of Taiwan and our ships at sea".
Taiwan President Tsai Ing-wen has called on the international community to "support democratic Taiwan" and "halt any escalation of the regional security situation."
The Biden administration says the US remains committed to the "one-China" policy that extends formal diplomatic recognition to Beijing while allowing robust informal relations and defence ties with Taipei.
However, the US criticised Beijing's actions in the Taiwan Strait, with White House press secretary Karine Jean-Pierre calling them "fundamentally irresponsible".