It’s not just a handshake, notice the tip of the head and bend of the back, it’s a bow. Notice also Castro did not bow back.

Presidents Obama and Castro share a handshake earlier at the #MandelaMemorial http://t.co/ZAjgCzU7PR (Getty Images) pic.twitter.com/XmiLaR3Mo9

— USA TODAY (@USATODAY) December 10, 2013