The Israeli military doubled down Saturday on its calls for the entire 1.1 million people in north Gaza to move south within the Palestinian territory ahead of an anticipated ground assault, despite U.N. warnings that the displacement would only worsen the humanitarian crisis in the Gaza Strip, already facing a siege and airstrikes. As photos showed Palestinians scrambling to flee in cars lining roads out of Gaza City, an Israeli military spokesman acknowledged that such a mass movement would take time but insisted “they have to start moving,” calling on Hamas to allow and facilitate the evacuation. U.S. officials said they negotiated a temporary opening at the Rafah border between Gaza and Egypt for American citizens seeking to flee, but a Palestinian border authority spokesperson and witnesses said it remained closed.