Why Melinda Gates thinks the U.S. must protect foreign aid

As President Trump stressed his “America-first” approach in remarks to the United Nations this week, Bill and Melinda Gates hosted a conference to unveil the results of a three-year-long Gates Foundation study on the world’s major health issues. Judy Woodruff spoke with Melinda Gates about the importance of U.S. leadership in world health, and how tech is affecting teens today.