Beijing has unveiled a new tactic on Taiwan, the democratic island it claims as its own, officials and experts say: large-scale drills with no fanfare to normalize a heightened military presence and let the U.S. know that China can act whenever it wants.

For four days this week, Taiwan went on alert in response to what it said was China's largest massing of naval forces in three decades around Taiwan and in the East and South China Seas.

China's military said nothing until Friday when it quoted ancient Chinese tactician Sun Tzu's "Art of War," a favourite of the communist republic's founder Mao Zedong.