The United Nations Relief and Works Agency has a history of hiring staff with connections to terrorist organizations while its schools erase Israel from maps, teach antisemitism and provide cover for Hamas weapons caches and terror tunnels. In short, UNRWA — the largest humanitarian organization in Gaza — bears direct responsibility for the extremism that fueled the Oct. 7 massacre of more than 1,200 Israelis. UNRWA’s flaws are well-known, but Washington still sent $344 million to the agency last year, making it the agency’s top donor. (President Trump had stopped funding it, but President Biden reversed that when he entered...