President Trump told reporters today that the disclosure of internal national security deliberations on a commercial messaging app was a minor transgression. He characterized the extraordinary security breach as “just something that can happen.”

Trump also stood by his national security adviser, Michael Waltz, who had inadvertently added a journalist to a group chat with other members of the president’s inner circle. In the chat, Defense Secretary Pete Hegseth and others shared information on timing, targets and weapons systems to be used in an attack on Houthi militants in Yemen. Here’s what to know about it.

During a Senate hearing this morning, the nation’s top two spy chiefs — who were both in the chat — acknowledged the sensitivity of information shared, but rejected responsibility. The administration claimed that nothing classified was shared; the journalist who was included in the chat said “they are wrong.”

Either way, disclosing even nonclassified national defense information in a nonsecure setting — like the app that was used, Signal — can still violate the 1917 Espionage Act.

Senate Democrats at today’s hearing expressed outrage: “This sloppiness, this disrespect for our intelligence agencies is entirely unacceptable,” Michael Bennet of Colorado said. Hakeem Jeffries, who leads Democrats in the House, urged Trump to fire Hegseth. Most Republicans on Capitol Hill reacted with a collective shrug. “I don’t think most Americans care one way or another,” Senator John Kennedy of Louisiana said.

In related news, the leaked chat showed European leaders how the Trump administration talks about them behind closed doors.