Factbox: Key facts on China-Taiwan relations ahead of Taiwan vote

(Reuters) - Taiwan goes to the polls on Saturday to elect a new president and parliament. China, which considers Taiwan a renegade province and part of its territory, will be watching the outcome closely. Following are key facts on ties between Taiwan and China: POLITICS - China has claimed self-ruled Taiwan through its "one China" policy since the Chinese civil war forced the defeated Nationalist forces to flee to the island in 1949 and has vowed to bring it under Beijing's rule, by force if necessary. - China, a permanent member of the U.N. Security Council formally known as the People's Republic of China, has about 170 diplomatic allies. Taiwan, formally known as the Republic of China, has 22. - Ties were badly strained when Chen Shui-bian from the Democratic Progressive Party (DPP) was Taiwan president from 2000-2008 because of his independence rhetoric, even as he tried to maintain positive relations with Beijing. - Relations warmed considerably after Ma Ying-jeou, from the China-friendly Nationalist Party, took office as president in May 2008. Ma steps down this year due to term limits. The DPP's Tsai Ing-wen is favored to win the presidential vote. In 2014, hundreds of students occupied Taiwan's parliament for weeks in protests nicknamed the Sunflower Movement. They demanded more transparency in trade pacts negotiated with China in the largest display of anti-China sentiment the island had seen in years. TRADE - China, including Hong Kong, is Taiwan's top trading partner, with trade totaling just over $170 billion in 2014, official data from Taiwan shows. About 40 percent of Taiwan's exports, such as tech components and chemicals, go to China. - Since 2008, when Taiwan President Ma came to power, Taiwan and China have signed about 23 agreements covering business and tourism, including an Economic Cooperation Framework Agreement in 2010, aimed to further deepen ties between the two sides. - China, with its 1.3 billion people, is also Taiwan's favorite investment destination with Taiwan companies investing over $100 billion there, private estimates show. About 55 percent of Taiwan's export orders are made in factories overseas, such as China. MILITARY - China and Taiwan have nearly gone to war three 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 harboring pro-independence views. Lee won by a landslide. - The military balance has shifted in China's favor. China's armed forces are 2.3 million strong while Taiwan has about 215,000 full-time troops. - China has deployed more than 1,000 short- and medium-range ballistic missiles as well as cruise missiles in coastal areas facing the Taiwan Strait, according to Taiwan's defense ministry. - The United States is obliged to help Taiwan with the means to defend itself under the U.S. Congress 1979 Taiwan Relations Act. China always reacts angrily to U.S. arms sales to Taiwan and has repeatedly demanded they stop. - China has more than 2,000 fighter aircraft, including Russian Su-30 and Su-27 fighters. Taiwan has about 300 fighter jets and the backbone of its air force is made up of U.S.-made F-16s, French-built Mirage 2000s and Ching-kuo Indigenous Defence Fighters. Sources: Reuters, Taiwan government, GlobalSecurity.org (Reporting by Beijing and Taipei newsrooms; Editing by Robert Birsel)