BEIJING, April 1 (Xinhua) -- The drills around Taiwan Island are a serious warning and an act of containment against "Taiwan independence" separatist forces, and a legitimate and necessary move to defend national sovereignty and uphold national unity, a Chinese foreign ministry spokesperson said on Tuesday.

The Chinese People's Liberation Army Eastern Theater Command on Tuesday started to conduct joint exercises around Taiwan Island.

In response to a relevant query, spokesperson Guo Jiakun told a daily press briefing that Taiwan is an inalienable part of the Chinese territory and the Taiwan question is purely China's internal affairs that brook no external interference.

The Democratic Progressive Party authorities are hellbent on seeking "Taiwan independence," and attempt to solicit external support for that agenda and divide the country, said the spokesperson.

"Such attempt is just futile and doomed to fail," Guo said. "The historical trend that China will and must achieve reunification is unstoppable."