JERUSALEM, July 21 -- A satellite image captured by Planet Labs on July 1 reveals what the Israeli military has since acknowledged: an earthen barrier more than 23 kilometers long cutting through the center of Gaza. The structure runs along what Israel calls the "Yellow Line," a ceasefire boundary established with Hamas last October. For Palestinians confined in a territory already stripped of infrastructure by more than twenty-one months of military operations, the wall marks what United Nations bodies and international rights organizations have characterized as a new phase of genocide.

The Israel Defense Forces confirmed the construction to the Associated Press after being confronted with Planet Labs satellite imagery, the first public...