Although the Republic of China (also known as Taiwan) is currently recognized by 13 UN member states, and possesses de facto sovereignty over its territory, it has never formally declared independence from the People's Republic of China. Opinion polling in Taiwan has generally shown a preference for maintaining the ambiguous status quo as long as possible. Various presidents of Taiwan have stated that a formal declaration is unnecessary because Taiwan is already independent. In the PRC, a formal declaration of Taiwanese independence is often cited as a "red line", raising the possibility of invasion.