It's official: South Korea and the US have officially begun war exercises, according to CNN, that may provoke further action from North Korea, and which China has warned against.

Here's the official stance from China, via China Daily:

"We hold a consistent and clear-cut stance on the issue. We oppose any party to take any military actions in our exclusive economic zone without permission," China's Foreign Ministry spokesman Hong Lei said in a statement days before the ROK- US joint drill.

Meanwhile, in Japan...

Kyodo News:

All members of Prime Minister Naoto Kan's Cabinet were on alert Saturday for developments in North Korea as South Korea and the U.S. prepared to start a four-day military drill Sunday in the Yellow Sea.

Cabinet members have been ordered by Kan to stay in Tokyo until Wednesday and be at their ministry offices within an hour in the event of a crisis.

Click here for a large photo gallery of the last US/Korea war drills >