Besides the United States, the countries represented are Argentina, Australia, Brazil, Britain, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea and Turkey.
The high profile event - drawing many world leaders and members of the media to one place - is an appealing target for terrorists and other extremists who want to make a point.
We witnessed a lot of security presence in and around the National Mall and we spotted an unknown (at least, to us) VIP family at the WWII Memorial, surrounded with a whole bunch of security and secret (what's in a name ?) service agents. Watch for yourself ...