Former acting Attorney General Sally Yates attempted to explain in one sentence the seriousness of her warnings about former national security adviser Michael Flynn.

“I’m not sure how much more of a siren you have to sound,” Yates said in a CNN interview with Anderson Cooper that aired Tuesday night.

Yates informed White House counsel Donald McGahn in January that Flynn, who discussed US sanctions against Russia with Russian ambassador Sergey Kislyak, was vulnerable to Russian blackmail. That’s because Flynn misled White House officials, including Vice President Mike Pence, about those conversations. In televised interviews, Pence repeated the misinformation Flynn provided and Russia knew about it.

Yates testified in a Senate Judiciary subcommittee hearing last week that she warned the White House about Flynn multiple times. Flynn kept his job for 18 more days before he was fired. Yates rebutted assertions from the White House that her admonitions about Flynn amounted to little more than a “heads up,” as described by White House press secretary Sean Spicer:

“When you call the White House counsel and say you’ve gotta meet with them that day about something you can’t talk about on the phone, and you tell them that their national security adviser may be able to be blackmailed by the Russians, and that you’re giving them this information so that they’ll take action, I’m not sure how much more of a siren you have to sound.”

Yates told Cooper she gave the White House information about Flynn so it could “act” and avoid being compromised at the hands of the Kremlin.

It was "absolutely" a national security issue, Yates said.