China and the United States Friday continued to probe eachother on the heels of China’s unilateral extension of a air defense zone that the other regional powers – Japan, South Korea, and Taiwan – refuse to recognize.

China launched two fighter planes Friday to investigate flights by a dozen U.S. and Japanese reconnaissance and military planes into China’s so-called “air defense zone” – most of which is legally in international territory.

China announced last week that all aircraft entering the zone – a maritime area between China, Taiwan, South Korea and Japan – must notify Chinese authorities beforehand, USAToday reported Friday. The Beijing government also said it would take unspecified defensive measures against those that don’t comply.

The United States and the neighboring nations said they will not honor the new zone, and have added that China’s unilateral act unnecessarily raised tensions.

The issue almost certainly will come up for discussion early next week when U.S. Vice President Joe Biden travels to Japan, China and South Korea.

At this juncture, the international relations and diplomatic community appears to be divided and a little perplexed over China’s unexpected assertiveness, with some seeing the move as ill-conceived and without an end game, while others characterized it as yet another chess move by China to assert itself more in regional affairs in the postmodern era.