As Israel Defense Forces continue their campaign against Hamas in Khan Yunis in Gaza’s south, the U.N. faced a question this week about just how much the organization knew about the underground tunnel system before the war.

Its official answer, delivered during a press briefing on January 17 by Secretary-General António Guterres’s spokesman: Nothing at all.

“Just to see it as an observer, to think that the UN had any understanding of what was . . . any information about those operations, I think, is: No is clearly the answer for that,” said Stephane Dujarric, the spokesman.

But Israel’s ambassador to the U.N., Gilad Erdan, begs to differ. Soon after that clip from the press conference circulated online, he took to Twitter to excoriate the U.N. for that claim.

“Nothing can be further from the truth!” he wrote, adding that he sent Guterres four letters detailing the construction of Hamas tunnels in the past two years. He posted two of those letters, in addition to an IDF-created infographic that depicted tunnel construction near a mosque, an UNRWA facility, and the Islamic University of Gaza.

Given the extent of U.N. agencies’ operations in Gaza, and existing questions about UNRWA’s ties to Hamas, the question is a pertinent one, and Erdan’s disclosures suggest that there might be more to the story than what Guterres’s office is letting on. Getting a more complete picture of the extent of U.N. entities’ knowledge of this and other aspects of Hamas’s activities in Gaza ought to be a major priority for lawmakers tasked with overseeing the U.S. budget for foreign aid and international organizations.