UPDATE (Feb. 13, 11:15 p.m.): National Security Advisor Michael Flynn has resigned after just 24 days after it was revealed he had misled Vice President Mike Pence and other members of the White House staff about his conversations with Russian officials before President Trump’s inauguration. He will be replaced as by retired Lt. General Joseph Keith Kellogg, Jr., according to a statement from the White House.

National Security Advisor Michael Flynn’s job appeared to be in jeopardy Monday after he acknowledged he may have discussed U.S. sanctions on Russia during an already controversial series of December phone conversations with Russian ambassador Sergey Kislyak.

But it’s not just the phone calls — the White House has reportedly seen a transcript of the conversation in question — that could cost Flynn his job. It’s also the fact that he may have misled Vice President Mike Pence about the content of the conversations.

In January, Pence told CBS News in no uncertain terms that Flynn hadn’t discussed the sanctions with the ambassador.

President Donald Trump is currently “evaluating the situation,” White House press secretary Sean Spicer said in a statement. “He’s speaking to Vice President Pence relative to the conversation the vice president had with General Flynn and also speaking to various other people about what he considers the single most important subject there is: our national security.”

If Flynn did discuss the sanctions, which were put in place in the waning days of the Obama administration in the wake of revelations about Russia’s alleged attempts to influence the U.S. election, it would be at best a breach of protocol and at worst a violation of laws forbidding private citizens from interfering in U.S. foreign policy. The FBI, however, reportedly reviewed transcripts of the phone calls and found no evidence of lawbreaking.

The Washington Post reported last week that in the midst of months of public denials by people in the Trump administration — including Flynn — that sanctions had been discussed, several national security sources told the paper that the discussions had in fact taken place.

Flynn reportedly apologized to Pence over the phone and in person.

A Kremlin spokesperson said Monday that Flynn, who had already received criticism for a photo of him sitting near Russian President Vladimir Putin at a 2015 banquet, did not discuss the lifting of sanctions with Kislyak.

According to the Huffington Post, National Security Council staffers confirmed that retired Gen. David Petraeus is being discussed as a potential replacement for Flynn. Petraeus previously served as CIA director, and commanded forces in Iraq and Afghanistan.