NPR's Eric Westervelt was among the first Western reporters to reach Iraq's capital during the 2003 U.S.-led overthrow of Saddam Hussein.
On March 20, 2003, the U.S. carried out its first airstrikes in Iraq.
In 2001, as the nation mourned those killed on 9/11, the government tried to find its footing to prevent more terrorist attacks. In the 20 years since, the nature of those threats has evolved.
The former presidents' comments come as polls show many Americans would be hesitant to receive a vaccine once one becomes available.