President Trump at the Group of 20 summit in Hamburg on Saturday. (Michael Ukas/European Pressphoto Agency)

Confusing civility with comity is a grave mistake in human or international relations. Yes, the Group of 20 summit issued a common communique after the leaders’ meeting. Some see this as an indication that some normality is being restored in international relations between the United States and other countries. The truth is that at no previous G-20 did the possibility occur to anyone that a common statement might not be agreed to by all participants.

Rather than considering agreement on a communique as an achievement, it is more honest and accurate to see its content as a confirmation of the breakdown of international order that many have feared since Donald Trump’s election. And the president’s behavior in and around the summit was unsettling to U.S. allies and confirmed the fears of those who believe that his conduct is currently the greatest threat to American national security.

The existence of the G-20 as an annual forum arose out of a common belief of major nations in a global community with common interests in peace, mutual security, prosperity and economic integration, and the containment of global threats, even as there was competition among nations in the security and economic realms. The idea that the United States should lead in the development of international community has been a central tenet of American foreign policy since the end of World War II. Since the collapse of the Soviet Union, the aspiration to international community has been an aspiration to global community.

Trump’s rhetoric has rejected the concept of global community and expressed a strong belief that the United States should seek better deals rather than stronger institutions and systems. It has become clear that Trump’s actions will match his rhetoric. The United States is now isolated globally on the question of how to deal with the grave long-run security threat of climate change. It has forced the G-20 to back way off of commitments to reject protectionism. And in part because of U.S. attitudes, the G-20 was mute on international migration at a time when refugee issues are more serious than at any moment in the past 50 years.

All of this is troubling enough. The elephant in the room, however, is the president’s character and likely behavior in the difficult times that come during any presidential term. Biographer Robert Caro has observed that power may or may not corrupt but it always reveals. Trump has yet to experience a period of economic difficulty or international economic crisis. He has not yet had to make a major military decision in a time of crisis. Yet his behavior has been, to put it mildly, erratic.

(Meg Kelly/The Washington Post)

The president chose hours before meeting with Russian President Vladi­mir Putin to cast doubt on judgments of the U.S. intelligence community regarding Russia’s interference in the 2016 election. On the brink of the most important set of international meetings of his presidency so far, he put forward the absurd idea that a main G-20 discussion item involved Hillary Clinton’s campaign chairman John Podesta, in the process making demonstrably false assertions about Podesta’s role.

It is rare for heads of government to step away from the table during major summits. When this is necessary, their place is normally taken by foreign ministers or other very senior government officials. There is no precedent for a head of government’s adult child taking a seat, as was the case when Ivanka Trump took her father’s place at the G-20 on Saturday. There is no precedent for good reason. It was insulting to the others present and sent a signal of disempowerment regarding senior government officials.

The president’s pre-G-20 speech in Poland expressed the sentiment that the primary question of our time was the will of the West to survive. Such a sentiment is inevitably alienating to the vast majority of humanity that does not live in what the president considers to be the West. Manichaean rhetoric from presidents is rarely wise. George W. Bush’s reference to an “axis of evil” is generally regarded as a serious error, not because the regimes he referenced were not evil but because his rhetoric drew our adversaries together. Invoking the idea of “the West against the rest,” as President Trump did, is a graver misstep.

A corporate chief executive whose public behavior was as erratic as Trump’s would already have been replaced. The standard for democratically elected officials is appropriately different. But one cannot look at the past months and rule out the possibility of even more aberrant behavior in the future. The president’s Cabinet and his political allies in Congress should never forget that the oaths they swore were not to the defense of the president but to the defense of the Constitution.

Read more:

David Rothkopf: The greatest threat facing the United States is its own president

Eugene Robinson: Trump’s dangerous thirst for a clash of civilizations

John Podesta: Why is Trump tweeting about me when he should be doing his job?

Michael Gerson: How to handle an unhinged president

Anne Applebaum: The Russian-American relationship is no longer about Russia or America