Israeli Prime Minister Benjamin Netanyahu lays a wreath during a ceremony marking the annual Holocaust Remembrance Day at the Hall of Remembrance at the Yad Vashem Holocaust memorial, in Jerusalem, Thursday, April 16, 2015. Israelis have stopped in their tracks, standing in silence as sirens pierced the air to remember the 6 million Jews who perished in the Nazi Holocaust during World War II. Pool Photo by Sebastian Scheiner/UPI
Israelis stand as a siren is heard during a ceremony marking the annual Holocaust Remembrance Day at the Hall of Remembrance at the Yad Vashem Holocaust memorial, in Jerusalem, Thursday, April 16, 2015. Israelis have stopped in their tracks, standing in silence as sirens pierced the air to remember the 6 million Jews who perished in the Nazi Holocaust during World War II. Pool Photo by Sebastian Scheiner/UPI
Israel's President Reuven Rivlin stands after laying a wreath during a ceremony marking the annual Holocaust Remembrance Day at the Hall of Remembrance at the Yad Vashem Holocaust memorial, in Jerusalem, Thursday, April 16, 2015. Israelis have stopped in their tracks, standing in silence as sirens pierced the air to remember the 6 million Jews who perished in the Nazi Holocaust during World War II. Pool Photo by Sebastian Scheiner/UPI
olocaust survivors and their relatives lay a wreath next to the names of concentration camps during a ceremony marking the annual Holocaust Remembrance Day at the Hall of Remembrance at the Yad Vashem Holocaust memorial, in Jerusalem, Thursday, April 16, 2015. Israelis have stopped in their tracks, standing in silence as sirens pierced the air to remember the 6 million Jews who perished in the Nazi Holocaust during World War II. Pool Photo by Sebastian Scheiner/UPI
sraeli Prime Minister Benjamin Netanyahu stands after laying a wreath during a ceremony marking the annual Holocaust Remembrance Day at the Hall of Remembrance at the Yad Vashem Holocaust memorial, in Jerusalem, Thursday, April 16, 2015. Israelis have stopped in their tracks, standing in silence as sirens pierced the air to remember the 6 million Jews who perished in the Nazi Holocaust during World War II. Pool Photo by Sebastian Scheiner/UPI
Holocaust survivors and their relatives lay a wreath next to the names of concentration camps during a ceremony marking the annual Holocaust Remembrance Day at the Hall of Remembrance at the Yad Vashem Holocaust memorial, in Jerusalem, Thursday, April 16, 2015. Israelis have stopped in their tracks, standing in silence as sirens pierced the air to remember the 6 million Jews who perished in the Nazi Holocaust during World War II. Pool Photo by Sebastian Scheiner/UPI