Donald Trump’s performance in Helsinki on Monday morning was certainly historic. On no other occasion since the founding of this country has an American president publicly demonstrated that he is a witting agent of a hostile foreign power — even as that country’s authoritarian ruler smirked beside him.

Standing at the podium with Vladimir Putin, Trump brazenly endorsed the Russian president’s denial of Kremlin interference in the 2016 presidential election. Only three days after his own appointees in the Justice Department announced charges against a dozen Russian agents, ratifying the long-held conclusions of US agencies, he told the assembled world media that he considered Putin’s word as good as  the counsel of his own intelligence chiefs.

He did nothing but genuflect to Putin during their joint press conference, meekly saying that he credited the Russian’s “strong and powerful denial” of interfering in the US election and that he “didn’t see any reason why they would.” Of course he personifies that reason, having spent the past year doing Kremlin dirty work against NATO, the European Union, and American institutions. He even praised Putin’s absurd “offer” to let the Russians investigate their own crimes against the United States.

On foreign soil, in the presence of an adversary, he blamed tensions with Russia on fellow Americans, from special counsel Robert Mueller to the Democratic National Committee — while absolving the Russian leadership of its aggressions in Crimea and elsewhere. In a breathtaking betrayal of his own self-proclaimed, patriotism, he declared Russia and America morally equivalent.

But even as Trump enacted this stunning sell-out of American principles and interests before a global audience, there were still Republican leaders willing to make excuses for him. With their cringing criticisms, they didn’t appear to comprehend that Monday’s events marked a dividing moment, between those who defend Trump despite his betrayal of our country and the oath — and those who know that he must go.

To describe Trump’s remarks in front of Putin as a “tragic mistake,” in the words of Senator John McCain, was itself a grave mistake. To say Trump doesn’t understand what the Russians did (and are doing), as his own staff whispers, is to promulgate yet another deception.

From scheduling a meeting with no policy agenda to insisting that nobody take notes of the conversation between Trump and Putin, the White House ignored policy and protocol. Only by casting aside all the usual safeguards could such a blatant hijacking occur. It is now obvious that the entire exercise — including Trump’s provocations against NATO, the European Union, and the government of the United Kingdom and up to his legitimizing of Putin — was a deliberate scheme to promote the interests of the Russian state against the West.

The obscure agenda became clear enough as soon as the two leaders began to speak. Trump had gone in to receive his instructions from Putin — and Putin had come out to pull his puppet’s strings in public.

To be sure, there are patriotic Republicans who understand the travesty of this presidency and are willing to stand up. Among them a few who have declined to run for office again, such as Senator Jeff Flake (R-AZ), who called Trump’s remarks “shameful.”

Far too many Republicans, however, delivered the most mealy-mouthed rebukes, whining that they are “disappointed” and “saddened.” The reliably craven Senator Lindsey Graham (R-SC) said that Trump’s encounter with Putin was “a missed opportunity.” The usual suspects such as Majority Leader Mitch McConnell (R-KY) and Speaker Paul Ryan (R-WI) just scolded Trump, impotently. (That’s what Republicans do, whenever they aren’t eagerly backing his racism and corruption.)

This is not a time for sadness or disappointment or passive whining. This is a time for determined action against a president whom we have known for many months is unfit for office and a present danger to democracy. Elected officials who swore an oath to uphold the Constitution and to defend the nation against all enemies, foreign and domestic, must ensure that he and his cronies are held accountable. If they fail, if they appease him, they too will be proved unfit.