EXPLAINER: Why is a Pelosi visit to Taiwan causing tension?

BEIJING (AP) — China is warning it will respond forcefully if U.S. House Speaker Nancy Pelosi proceeds with a planned visit to Taiwan. Pelosi would be the highest ranking U.S. politician to visit the self-governing island democracy since 1997. China claims Taiwan as its own territory to be annexed by force if necessary, and its military buildup in recent years has largely been oriented toward such a mission. Beijing objects to all official contact between Taipei and Washington, but this time, the stakes appear to be higher. China marks an important military anniversary on Aug. 1 and later this year will open an important party congress where leader Xi Jinping is expected to seek an unprecedented third term.