TOKYO -- Japan became a full-fledged participant Monday in NATO's cybersecurity war games, as Tokyo and Western nations eye potential hacking threats from China.

The Cyber Coalition exercise, which lasts until Friday, poses scenarios including cyberattacks during cross-border conflict as well as compromised state computer systems. One scenario involves participants striking back against a virtual enemy.

Japan upgrades its role from observer status, a position the country held between 2015 and 2018, as neighbor China reportedly builds its cyberwarfare capabilities.

"Japan has little experience in international exercises in the cyber field," a Defense Ministry official said. "There are multiple issues we need to overcome, like the language barrier. Participation in multilateral exercises is very meaningful, since it lets us prepare for actual operations."

Japan's cyber defenses have faced criticism as trailing those of Western nations, raising the possibility that U.S. and European nations could suffer damage as a result of an attack on Japanese computers. Japan shares not only geographic proximity with China, but also deep economic ties.

China is home to hacker groups whose numbers are said to grow by the year. They have been linked to attacks on government and corporate servers worldwide. Beijing is thought to have created a cyberwarfare unit as far back as 2015 as part of a sweeping reorganization of its military.

U.S. and European observers believe China now possesses cyberattack capabilities that rival those of Russia. Concerns over data breaches have prompted Washington in particular to lobby other nations against using Chinese-made telecommunications equipment for their fifth-generation wireless infrastructure.

The NATO alliance's Cyber Coalition, with a command center in Estonia, is one of the world's largest exercises of its kind. The more than 30 participants this year include the U.S., European Union and Ukraine.

Personnel from Japan's Defense Ministry and the Self-Defense Forces logged in through the ministry. The team of roughly 20 shared data and gave input on decision-making.