The Israeli Defense Forces are reporting that “terrorist organizations” have shot mortars at a new floating pier for humanitarian aid off the coast of Gaza City, which American troops plan to start assembling as early as this weekend. 

The pier came under fire Wednesday while United Nations officials were touring the area, according to Israeli press reports, though none of them were hurt. “The terrorist organizations continue to systematically harm humanitarian efforts while risking the lives of UN workers,” the IDF said in a statement after the attack, “while Israel allows the supply of aid to the residents of the Gaza Strip.”

President Biden announced construction of the pier and floating causeway closer to the shore during his State of the Union address in March. He pledged to get more aid into Gaza — aid now enters through two border crossings in the south — while vowing there would be “no U.S. boots on the ground.” 

The attack highlights the perils of this initiative. Hamas says anyone who is distributing aid to Gaza in collaboration with Israel is a traitor and at risk of death.

“We understand there is risk and we do everything we can to mitigate the risk,” the Chairman of the Joint Chiefs of Staff, Air Force General CQ Brown Jr., said Thursday, “by putting in capability [and] working with the Israelis.”

The Pentagon estimates that it will take American troops 10 to 14 days to assemble the pier. That timeline could be slowed down, though, given the challenges of construction without American military personnel stepping into Gaza. ABC News reported people familiar with the plans saying that the pier could cost America $180 million or more. 

Wednesday’s news comes as Israel prepares for a ground invasion of Rafah, which it says is now the main stronghold of Hamas terrorists in Gaza. The heads of the Israeli military and internal security service are working with Egyptian officials to evacuate civilians from Rafah to “humanitarian zones” in other parts of Gaza.