Why are there fears China and Taiwan could go to war-

A dramatic rise in the number of aerial sorties over the sea separating the Chinese mainland from Taiwan has served as a reminder that the strait has the potential to be one of the most dangerous places on Earth. A reported 149 incursions in four days by People’s Liberation Army planes into Taiwan's air defence zone have left the de-facto independent island on high alert as it warned that China could be capable of invading by 2025. As global leaders keep a close eye on the worsening relations in the region, Guardian correspondent Helen Davidson explains why and how tensions could escalate into war