U.S. House Speaker Nancy Pelosi’s trip to Taiwan may have been brief, but it wasn’t short on controversy. She's the most senior U.S. official to visit Taiwan in decades — but many worry her visit will fan the flames of an already tense relationship between the self-governed island and China, which claims Taiwan as its territory and opposes any engagement by Taiwanese officials with foreign governments. Ahead of Pelosi's visit, China ramped up military drills near Taiwan, and Beijing has vowed to hold even more military exercises over the next several days. Some experts are calling it the most hazardous escalation between the two regions since the 1990s. Today Christian Shepherd, a Washington Post correspondent based in Taipei, explains how tensions between China and Taiwan got to this point, and why Pelosi’s visit was so controversial.