Terrorism has changed but remains a threat

Twenty years ago, the United States was intently focused on terrorism. The 9/11 attacks had killed 3,000 Americans and profoundly shaken our national sense of safety and security. President George W. Bush declared we were fighting a “war on terror” and vowed we would defeat terrorist organizations.

Since then, we have taken important steps to keep our country safe, and they have been largely effec...