Participants react as they observe a fly past during the NATO Summit in Warsaw
(L-R) Croatia's President Kolinda Grabar-Kitarovic, Poland's President Andrzej Duda, NATO Secretary-General Jens Stoltenberg, Lithuania's President Dalia Grybauskaite, German Chancellor Angela Merkel, France's President Francois Hollande and Turkey's President Tayyip Erdogan react as they observe a fly past during the NATO Summit in Warsaw, Poland July 8, 2016. REUTERS/Kacper Pempel