The novel coronavirus pandemic, which has caused group infections on a United States aircraft carrier, is casting a shadow over the deterrent capability of Japan and the US in the Indo-Pacific region. 

While the US military's deployment capacity has been reduced by the infections, China has stepped up provocative maritime activities.

Alarmed by the developments, Japan and the US are working to demonstrate their presence through joint defense exercises in a bid to prevent a vacuum of power in the strategic region.

China has continued to exert military pressure on the Nansei island chain in southwestern Japan despite the spread of the coronavirus, Japanese Defense Minister Taro Kono said in an online lecture in Tokyo on Monday.

On April 11, six Chinese military vessels, including the aircraft carrier Liaoning, sailed between the main island of Okinawa Prefecture and the island of Miyako in southwestern Japan and subsequently carried out a drill in the South China Sea.

The operations, which came at a time when the US aircraft carrier Theodore Roosevelt has been stopped due to the coronavirus infections, sent shock waves through the Japanese and US security communities.

Hiroshi Yamamura, chief of staff of the Japanese Maritime-Self Defense Force, said the Chinese Navy has not been affected significantly by the coronavirus and been continuing its activities.

Self-Defense Forces aircraft has been scrambled against Chinese planes 152 times in January-March. The number of days in March in which Chinese government ships intruded into waters around the Senkaku Islands in Okinawa doubled from a year before. China claims the Japanese-administered islands, calling them Diaoyu.

In the meantime, the MSDF's Akebono destroyer conducted a joint drill with the United States' America-class amphibious assault ship in the East China Sea on April 10-11.

The assault ship, which carries Marines and the F-35 state-of-the-art stealth fighter, is used in operations to recapture islands. The involvement of the ship in the joint exercise can send a strong message, a senior MSDF officer said.

Also, the MSDF destroyer Teruzuki has taken part in a joint telecommunications drill with a US vessel in waters off the Malay Peninsula.

The Japanese government plans to strengthen cooperation with friendly nations in Europe and Asia as well.

Kono held phones talks with his French counterpart, Florence Parly, on Friday and shared the recognition that the Chinese military's movements are a threat to the region. France has territories in the Pacific.

As it is difficult to predict when the US aircraft carrier will return to normal deployment amid the global pandemic, Japanese and US security officials are likely to have to remain nervous for some time.