And that is why I’m coming to you few good men.

I’m not asking you to quit; I’m asking you to act — to collectively or individually sit the president down and make clear that you can’t effectively advance our national security unless he does the right thing and apologizes to President Obama, and unless he releases his tax returns to eliminate any questions regarding what we now know is already an eight-month-old F.B.I. investigation into possible collusion between the Kremlin and Trump’s campaign to hack our last election.

Surely none of you believes it’s O.K. for a president to smear his predecessor and then stand by the charge even when it is exposed as a lie.

I’m now in Paris, after almost a week in the United Arab Emirates. I have to tell you, the world is watching.

I had several young Arabs from around the region tell me that when America lets its own leader get away with lying, hiding information and smearing the press or a political opponent, it is taken as a license by all Middle Eastern leaders, or the leaders of Turkey or Russia, to do the exact same thing and say: “See, the American president does it, why shouldn’t we?”

There is a profound sense of loss in the world today that the optimistic, inclusive, generous, rule-of-law America that so many foreigners grew up admiring is disappearing. A poll by Germany’s ARD media group found that the percentage of Germans who think the U.S. is a “trustworthy ally” dropped from 59 percent in November to 22 percent last month.

Trump inherited a “daunting inbox” in foreign policy, but unfortunately “he is making it much worse,” said Richard Haass, president of the Council on Foreign Relations and author of a valuable new book, “A World in Disarray: American Foreign Policy and the Crisis of the Old Order.” Trump’s embrace of “protectionism and hostility to immigrants — when the real culprit is new technologies that are eliminating existing jobs and an educational system that is not preparing Americans for new ones — and his rhetoric and policies are increasing doubts overseas about American dependability.” Without an urgent course correction, added Haass, we could end up “not with America first, but with America alone.”