The government in Taiwan, officially known as the Republic of China, has ruled the island since retreating there after losing the Chinese civil war to Mao Zedong's communist forces. Taiwan has never declared independence—a move China has threatened war over—but functions as a sovereign state with its own democratic government, military and defined territory.
To establish diplomatic relations with Beijing, China requires countries to recognize the "One China" principle and cut official ties with Taiwan. For more than four decades, the U.S. has followed a "One China" policy, acknowledging—but not endorsing—China's claim over the island of 23 million and not expressing support for de jure Taiwan independence.
