U.S. President Barack Obama lays a wreath at the Ghetto Monument in Warsaw May 27, 2011. REUTERS/Franciszek Mazur/Agencja Gazeta/Handout (POLAND – Tags: POLITICS) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. POLAND OUT. NO COMMERCIAL OR EDITORIAL SALES IN POLAND