Taiwan on Thursday conducted live-fire war drills along its west coast amid mounting fears that Chinese President Xi Jinping could use military force to annex the democratic island.

Artillery batteries, self-propelled artillery weapons, attack helicopters, and main battle tanks fired at targets off the west coast city of Taichung, while the island's air force operated French-made Dassault Mirage 2000 fighter jets.

The war exercise followed a new report from the Pentagon outlining concerns about Beijing’s expanding military might, including a possible invasion of Taiwan.

"China ... believes that U.S. military presence ... in Asia seeks to constrain China’s rise and interfere with China’s sovereignty, particularly in a Taiwan conflict scenario," the Pentagon report said.

In a meeting with US Chief of Naval Operations Admiral John Richardson in Beijing on Tuesday, China’s chief of staff Li Zuocheng warned about foreign forces coming to Taiwan’s help.

The US is Taiwan’s primary source of heavy military hardware and legally bound to respond if China invades the island.

China's armed forces will “pay any price” to ensure China’s sovereignty, Zuocheng told Richardson at their meeting. China considers Taiwan, which split from the mainland amid civil war in 1949, as part of Chinese territory.

The trigger for the military drills could have been due to Taiwan President Tsai Ing-wen, recently rejected requests from President Xi for the island to move towards "unification" with China.

Major General Chen Chung-chi, the spokesman for Taiwan's Defense Ministry said the military is updating its exercises to reflect the possibility of an amphibious invasion by China.

"We exercise the way wars are fought ... so that we will be capable and confident in the defense of our country," Chen told journalists in Taipei on Wednesday. "We are ready to face an enemy threat at any time."

The drills come amid rising pressure from President Xi declaring, "Renufication is the historical trend and the right path, Taiwan independence is...a dead end," during an address this month.

China Uncensored provides an informational video showing how China has a plan to invade Taiwan by 2020.