Independent counsel Robert Mueller has indicted 13 Russians for waging information warfare against the United States by tampering with the American electoral process in 2016. Sadly but predictably, America’s commander-in-chief did not respond by rallying his country to meet the threat. Rather, President Donald Trump went out of his way to dodge the question of Russian interference, while publicly attacking the officials and institutions that have had the temerity to confront that issue head-on.

Observers from both sides of the political spectrum, appropriately, deplored Trump’s abdication of his duty to defend the nation. Yet this episode also has a broader significance: It gives the lie to the idea that the U.S. can have a constructive foreign policy while a profoundly destructive individual is president.

This idea has commanded a respectable following since Trump took office. The fact that Trump appointed mostly mainstream figures to key positions, and that his “America first” agenda has been considerably watered down in practice, has led a number of Republican policy hands to argue that the administration’s actions have been broadly praiseworthy even if the president’s rhetoric has not. Elliott Abrams, who worked for Presidents Ronald Reagan and George W. Bush, has argued that Trump has adopted a “fairly familiar Republican approach to foreign policy.” Matthew Kroenig, who advised the Mitt Romney and Marco Rubio presidential campaigns, contends that the administration has “the right people” and “the right positions.”

As I point out in my new book, “American Grand Strategy in the Age of Trump,” these arguments are not entirely wrong. Despite his campaign promises, Trump has not (yet) launched an all-out trade war with China, torn up U.S. alliances, or quit the North American Free Trade Agreement and the World Trade Organization. In these and other cases, his advisers have persuaded him to take a more moderate course.

Even with respect to Russia, a similar pattern has prevailed. Trump continues to talk up the dangerous fantasy of a rapprochement with Putin, yet his administration has increased funding for forward defense in Eastern Europe, resolved to provide lethal weaponry to Ukraine, and pursued other policies that Russia hawks should welcome.

It is thus true that there are pockets of normality in U.S. policy, even in the age of Trump. What this most recent manifestation of Trump’s bizarre stance toward Russia demonstrates, though, is that there is only so much containing, circumventing and moderating of a president who refuses to take his duties seriously.

It is important to stipulate here that we don’t know precisely why Trump is so reflexively dismissive of the mountains of concrete evidence documenting a deliberate Russian campaign to suborn American democracy. It could be that Moscow possess some compromising information on him or his prior business dealings. It could be that he genuinely believes he is a diplomatic genius who can strike a grand bargain with Russian President Vladimir Putin. It could be that Trump perceives any discussion of Russian electoral interference as an assault on his presidential legitimacy, and that he is simply too narcissistic to separate that issue from the broader national wellbeing.

Whatever the answer, Trump’s refusal to personally take on the information-warfare threat from the Kremlin is crippling U.S. policy in several ways.

First, it is discouraging concrete — and badly needed — responses to the threat. If, as seems likely, there are covert efforts that the intelligence community might undertake either to strengthen U.S. defenses or retaliate against Russian attacks, they would likely require additional legal authorities or presidential findings — neither of which this president is likely to support.

In the same vein, European officials have privately advocated greater trans-Atlantic cooperation to address the common danger posed by Russian meddling, but Trump’s indifference to that danger has limited the possibilities for such collaboration. Within the U.S. government, too, Trump’s attitude is raising the political costs and risks for advisers who seek to counter Russian measures. It is hardly surprising, then, that the Department of Homeland Security and other government agencies have made so little progress in hardening American defenses, even as intelligence officials have warned in increasingly dire tones that the Russians will seek to re-run the 2016 playbook in 2018. In the American system, decisive action generally requires presidential buy-in, and that has been sorely lacking.

Second, Trump is making it impossible for the U.S. to issue clear and believable deterrent threats. Information warfare and cyberattacks are inherently difficult to prevent, and so a better approach may be to go on the offensive, by threatening sharp retaliation through reciprocal cyberattacks or other measures. But such threats only work if they are seen to be credible, and why would anyone believe that Washington would inflict significant costs on Russia — and risk significant escalation of bilateral tensions — when Trump declines even to acknowledge that a threat exists?

Third, the president’s position is not just having pernicious effects within the executive branch; it is undercutting the broader national will and consensus needed to meet a grave security challenge. The genius of the Russian meddling in 2016 was that it avoided the normal “rally around the flag” effect that often occurs in the wake of a foreign attack. Instead, it pitted Americans against one another — Republicans against Democrats, state authorities against the federal government.

Another president would surely see it as his or her duty to surmount such divisions by issuing a broad, nonpartisan call to arms. Yet Trump is aggressively politicizing the issue, impugning the reputations of the agencies that are striving to defend U.S. democracy, and thus making it far less likely that the country will achieve unity in the face of danger.

Finally, Trump’s performance is reminding us of the critical role the American president plays in leading not just his own country but the larger “free world,” and how powerfully the absence of that leadership is felt at times of crisis. The liberal international order America has anchored for generations is facing an array of challenges from authoritarian, revisionist powers, namely Russia and China. Yet rather than placing himself at the vanguard of the international response, Trump is shirking that obligation. And in doing so, he is exacerbating the demoralization and division that is weakening the liberal West just as the dangers are mounting.

To borrow from former French President Jacques Chirac, the position of leader of the free world is indeed vacant today — no matter how hard Trump’s advisers labor to make it seem otherwise.

Hal Brands is the Henry A. Kissinger distinguished professor at the Henry A. Kissinger Center for Global Affairs at Johns Hopkins University’s School of Advanced International Studies and a senior fellow at the Center for Strategic and Budgetary Assessments. His latest book is “American Grand Strategy in the Age of Trump.”