WASHINGTON – The revelation that President Donald Trump’s most senior national security officials posted the specifics of a military attack to a chat group that included a journalist hours before the attack took place in Yemen has raised many questions.

Among them is whether federal laws were violated, whether classified information was exposed on the commercial messaging app, and whether anyone will face consequences for the leaks.

Here’s what we know so far, and what we don’t know.

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KNOWN: Signal is a publicly available app that provides encrypted communications, but it can be hacked. It is not approved for carrying classified information. On March 14, one day before the strikes, the Defense Department cautioned personnel about the vulnerability of Signal, specifically that Russia was attempting to hack the app, according to a U.S. official, who was not authorized to speak to the press and spoke on the condition of anonymity.

One known vulnerability is that a malicious actor, if they have access to a person’s phone, can link their own device to the user’s Signal — and essentially monitor messages remotely in real time.

NOT KNOWN: How frequently the administration and the Defense Department use Signal for sensitive government communications, and whether those on the chat were using unauthorized personal devices to transmit or receive those messages. The department put out an instruction in 2023 restricting what information could be posted on unauthorized and unclassified systems.

At a Senate Intelligence Committee hearing on Tuesday, Director of National Intelligence Tulsi Gabbard would not say whether she was accessing the information on her personal phone or government-issued phone, citing an ongoing investigation by the National Security Council.

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KNOWN: The government has a requirement under the Presidential Records Act to archive all of those planning discussions.

NOT KNOWN: Whether anyone in the group archived the messages as required by law to a government server.

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KNOWN: The chat group included 18 members, including Jeffrey Goldberg, editor-in-chief of The Atlantic. The group, called “Houthi PC Small Group,” likely for Houthi “principals committee” — was comprised of Trump’s senior-most advisers on national security, including Gabbard, Defense Secretary Pete Hegseth, Secretary of State Marco Rubio and CIA Director John Ratcliffe. The National Security Council said the text chain “appears to be authentic.”

NOT KNOWN: How Goldberg got added. Each agency principal named a staff member to be added to the chat, and Waltz named his staffer Alex Wong, as taking the lead in assembling the team that would monitor the attacks. It was not clear if Waltz himself, or a staffer managing Waltz’s Signal account, sent Goldberg the invitation.

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KNOWN: Just hours before the attack on the Houthis in Yemen began, Hegseth shared details on the timing, targets, weapons and sequence of strikes that would take place.

NOT KNOWN: The classification level of this information. In the Senate hearing, both Gabbard and Ratcliffe referred questions to Hegseth on whether classified information was posted to the unclassified Signal chat. Hegseth so far has not answered questions on whether the information he shared on Signal during that messaging was classified.

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KNOWN: Hegseth has adamantly denied that “war plans” were texted on Signal, something that current and former U.S. officials called “semantics.” War plans carry a specific meaning. They often refer to the numbered and highly classified planning documents — sometimes thousands of pages long — that would inform U.S. decisions in case of a major conflict, such as if the United States is called to defend Taiwan.

But the information Hegseth did post — specific attack details selecting human and weapons storage targets — was a subset of those plans and was likely informed by the same classified intelligence. Posting those details to an unclassified app risked tipping off adversaries of the pending attack and could have put U.S. service members at risk, multiple U.S. officials said.

Sharing that information on a commercial app like Signal in advance of a strike “would be a violation of everything that we’re about,” said former Defense Secretary Chuck Hagel, who served under President Barack Obama.

NOT KNOWN: If anyone outside the messaging group got access to the Signal texts.

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KNOWN: Hegseth is cracking down on unauthorized leaks of information inside the Defense Department, and his chief of staff issued a memo on March 21 saying the Pentagon would use polygraph tests to determine the sources of recent leaks, and prosecute those found to have disclosed unauthorized information.

NOT KNOWN: Whether Hegseth will take responsibility for the unauthorized release of national defense information to a journalist regarding the attack plans on the Houthis.