"Israeli officials complained privately to U.S. officials that Waltz’s texts became public."

"The identity of a person in Yemen who was supplying information in real-time about the strikes would likely be carefully protected."

As in highly classified.

https://www.wsj.com/politics/national-security/israel-supplied-intelligence-in-airstrike-discussed-in-signal-chat-officials-say-9a9e0abf