Story highlights Last week, a day after James Clapper testified before the Senate, Trump fired James Comey

Juliette Kayyem: Since then, Clapper has become a staunch critic of Trump and defender of American democracy

CNN national security analyst Juliette Kayyem is the author of the best-selling "Security Mom: An Unclassified Guide to Protecting Our Homeland and Your Home." She is a professor at Harvard's Kennedy School, a former assistant secretary of Homeland Security in the Obama administration, host of the national security podcast The SCIF and founder of Kayyem Solutions, a security consulting firm. The opinions expressed in this commentary are hers.

(CNN) Last week, when he testified before the Senate Judiciary subcommittee, James Clapper, former director of national intelligence, had the disposition of someone who looked like he had retired for a reason and planned to go straight back. He made his points, answered many questions and perhaps hoped that would be the end of his contribution on the Trump/Russia story.

There should be little doubt that the extraordinary days that followed his original testimony -- most notably, almost exactly 24 hours later, President Donald Trump's firing of FBI Director James Comey -- began in some measure because of his understated but highly damning testimony.

Juliette Kayyem

Now, as he voluntarily makes the media circuit since the firing, Clapper sees the consequences of Trump's actions as so threatening to our democracy that he is not likely to recede soon.

Let's go back to last week; yes, it was only last week. All eyes were on former Deputy Attorney General Sally Yates as she testified about what she told the White House regarding former national security adviser Michael Flynn and his potentially compromising ties to foreign governments.

Yates made an impression, but it was Clapper who drew the real spotlight

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