CNN national security analyst John Kirby, a retired rear admiral in the US Navy, was a spokesman for both the State and Defense departments in the Obama administration. The opinions expressed in this commentary are his.

(CNN) The Russians meddled in the 2016 election. We haven't held them to account for it. They will do it again.

If you happen to be one of those few Americans who still don't believe any of that (hello, Mr. President), you need to take a look at what Navy Admiral Mike Rogers told lawmakers Tuesday.

"The Intelligence Community concluded last year that Russian actors, with the knowledge of senior decision-makers, employed influence operations to interfere with the US presidential election in 2016," said Rogers, the head of the National Security Agency and US Cyber Command.

He said the Kremlin did this by employing hackers who stole personal communications, which were then leaked to new outlets. They also created both fake social media personas and news items on all sides of the issues to sew discord and confusion.

"This," he warned, "threatens the foundations of democracy, making it difficult ... to craft common measures for countering Russia's aggressive actions in its near-abroad and its repression at home."

When pressed by senators about what the administration was doing to craft those "common measures," Adm. Rogers was forced to admit ... not a whole lot.

"They haven't paid a price, at least, that's sufficient to get them to change their behavior."

It reminds one of what Lord Palmerston , the great 19th century British diplomat, once said about the Russians:

"It has always been the policy and practice of the Russian government to expand its frontiers as rapidly as the apathy or timidity of neighboring states would permit, but usually to halt or frequently recoil when confronted by determined opposition; then to await the next favorable opportunity to spring upon its next victim."

Palmerston was referring, of course, to Moscow's geographic ambitions during the Victorian age. We can certainly see afresh his wisdom in Russia's modern-day violations of Ukrainian sovereignty. But the essential truth of Palmerston's warning applies as well to Russia's orchestrated and aggressive ambitions in cyber space.

Mr. Putin will only stop this malicious meddling when confronted by a "determined opposition" to it. And thus far, as the admiral testified, Putin's felt nothing of that.

President Trump still cannot bring himself to openly acknowledge, much less criticize, Russia for its cyber crimes. He has not ordered his intelligence or law enforcement chiefs to combat those crimes. And he has not implemented the punitive bipartisan sanctions against Russian entities that he himself -- albeit reluctantly -- signed into law.

Adm. Rogers assured lawmakers today that "we're taking steps, but we're probably not doing enough."

One reason for that, he confessed, is that he hasn't been given the necessary authorities -- legal and direct orders, as it were -- to more aggressively target the threat at its source ... in Russia.

"I need a policy decision that indicates there is specific direction to do that," Rogers said. "The President ultimately would make this decision in accordance with a recommendation from the Secretary of Defense."

Right he is. Neither the new National Security Strategy nor National Defense Strategy say much about so-called offensive cyber capabilities. But the NSS makes clear that the United States "will impose swift and costly consequences on foreign governments, criminals, and other actors who undertake significant malicious cyber activities."

Those consequences have to be the result of a policy decision. And Adm. Rogers doesn't make policy.

To be sure, the administration can -- and should -- have the debate as to the advisability of more aggressive cyber options. There are also other, noncyber-related ways to retaliate against state and nonstate actors -- such as those pesky sanctions the President won't implement. All options should be fairly heard.

But that's the problem right now. Nothing is being heard, much less discussed, regarding this looming threat to our democracy. So convinced is he that evidence of Russian meddling taints his legitimacy, Trump refuses in nearly every way to face the issue squarely and dispassionately -- the way any good commander in chief would face a national security threat.

Best we can tell, the President hasn't even convened a single National Security Council meeting to address the matter.

For his part, Adm. Rogers said he hasn't asked for additional authorities. He no doubt has good reason for that, reasons the public are probably not meant to know. Given the admiral's long record of service and his reputation for candor, we should not leap to the conclusion that one of his reasons is the President's intransigence.

But absent more context and an adequate explanation for why the administration has failed to enact "swift and costly consequences" on Russia, the American people could be forgiven for believing that we are leaving ourselves vulnerable. They might be forgiven for worrying that we will fall prey to the same ill-confidence in our electoral process, the same crassness in our public discourse, and the same distrust in our public institutions that Russia's attacks have heretofore engendered. Indeed, six in ten of those Americans surveyed in a new CNN poll said they lacked confidence the President is doing enough to stop outside meddling in US elections.

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It is way past time for Trump to reassure the citizens of this country that he takes this matter seriously, and that he will do all that is required to defend our constitution, as his oath stipulates, "against all enemies, foreign and domestic."

Palmerston had it right all those years ago. Even when effectively confronted, Russia will await the "next favorable opportunity to spring upon its next victim."

Russia has not been effectively confronted. And if we don't start doing something soon to protect our democratic system, we must content ourselves with the dubious distinction of being both Putin's last -- and next -- victim.