Why Does China Want Taiwan?

When President Trump meets his Chinese counterpart, Xi Jinping, Taiwan is almost certainly going to come up. And few issues in diplomacy are more complicated than the status of the self-governing island that China claims as its own. Ahead of the summit, White House officials rejected speculation that Mr. Trump could set U.S. policy on Taiwan on a new course during this trip. But even seemingly slight changes in wording can count, especially if they are uttered by an American president in Beijing. Will Mr. Trump, with his improvisational style,…