CHINA has claimed Taiwan through its "one China" policy since the Chinese civil war forced the defeated Kuomintang, or Nationalists, to flee to the island in 1949, and has vowed to bring it under Beijing's rule, by force if necessary.

Following are key facts on ties between Taiwan and China as military tensions rise again:

POLITICS

Since the Democratic Progressive Party's Tsai Ing-wen first became president in 2016, Taiwan-China ties have soured again, with China cutting off a formal dialogue mechanism, flying fighters and bombers near Taiwan, forcing foreign firms to refer to Taiwan as part of China on their websites, and whittling away Taiwan's diplomatic allies.

Beijing believes Tsai, who won re-election by a landslide last year, wants to push Taiwan's formal independence, a red line for China. She says Taiwan is already an independent country, the Republic of China, its official name, and that the government will defend the island's freedom and democracy.

The Kuomintang party, which favours close ties to China, had been in power before Tsai. Relations warmed considerably after its leader, Ma Ying-jeou, won the presidency in 2008. Re-elected in 2012, Ma went onto hold a landmark meeting with Chinese President Xi Jinping in Singapore in 2015.

MILITARY

China and Taiwan have nearly gone to war several times since 1949, most recently ahead of the 1996 presidential election. Then, China carried out missile tests in waters close to the island hoping to prevent people voting for Lee Teng-hui, who China suspected of harbouring pro-independence views. Lee won convincingly.

Taiwan says China has thousands of short- and medium-range ballistic missiles as well as cruise missiles pointed at Taiwan, and that China runs a sophisticated online disinformation campaign to undermine confidence in the government.

Taiwan and China last joined battle on a large scale in 1958, when Chinese forces carried out more than a month of bombardments of the Taiwan-controlled Kinmen and Matsu islands, including naval and air battles.

The United States is obliged to help provide Taiwan with the means to defend itself under the 1979 Taiwan Relations Act. China always reacts angrily to U.S. arms sales to Taiwan and has repeatedly demanded they stop. China has blamed the United States for the latest tensions due to its support for Taiwan's government.

China has the world's largest armed forces, and they have been rapidly modernising, adding stealth fighters, aircraft carriers and new submarines, under an ambitious programme overseen by Xi.

Taiwan's far smaller military is mostly supplied by the United States, though Tsai has bolstered domestic production, including developing long-range missiles and new, heavily-armed "aircraft carrier killer" warships.

Taiwan's air force in particular is well trained, but experts say the island could likely only hold out for a few days in the event of a Chinese attack unless the United States quickly came to its aid.