This week, leaders from the 28 member countries of the North Atlantic Treaty Organization will gather in Chicago for a summit aimed at discussing international security and the war in Afghanistan. This will be the 25th time NATO has held a summit and the first time the United States has hosted the event since 1999. It will also be the largest such event in the organization’s history. Throughout the day on Sunday and Monday, the U.S. State Department will broadcasts events with President Obama and foreign leaders. Click here to watch .