The Army’s 7th Transportation Brigade and other units are building a floating dock off the Gaza coast to provide food and other desperately needed assistance to residents of Gaza. The aid is needed because Israel has sharply restricted land routes into Gaza, slowing the flow of aid to a trickle. It’s a complex operation, involving as many as 1,000 U.S. troops, and it won’t happen overnight. Air Force Maj. Gen. Pat Ryder, the Pentagon press secretary, told reporters it will take weeks for this to come together. Some officials say it will take about two months. And beyond the logistical challenges, the operation will depend on Israel’s cooperation, which isn’t assured.