The Chinese naval activity comes as Mr. Obama visits Alaska and the Arctic region to highlight climate change. The naval operation also comes just before Chinese President Xi Jinping presides over a World War II Victory Day parade on Thursday that the U.S. and its allies fear is being used to showcase China’s new military strength and ambition.
A huge military parade rolls through Tiananmen Square on Thursday as Beijing commemorates the 70th anniversary of Japan's WWII defeat, but major Western leaders are staying away from the show of strength.
President Xi Jinping will oversee the spectacle featuring 12,000 Chinese soldiers, 500 pieces of hardware and almost 200 aircraft, which comes as Beijing takes a more assertive diplomatic stance.
Key leaders from Western democracies will be absent, such as US President Barack Obama, German Chancellor Angela Merkel and Japanese Prime Minister Shinzo Abe, who has drawn Beijing's ire for beefing up his country's security policies.
Xi is China's commander-in-chief as the chairman of the Communist Party's Central Military Commission, since the People's Liberation Army (PLA) is technically the armed force of the Party.
Under him, Beijing is moving farther away from former leader Deng Xiaoping's dictum to "hide one's capabilities, bide one's time" and is becoming more willing to take harder lines, both externally and against domestic opponents.
It is engaged in high-profile maritime disputes with neighbours in the South China Sea, where it is building artificial islands and facilities with military uses, and with Japan over disputed outcrops.