But now Emmanuel Macron, the President of France, has tried something more complicated.
Apparently on a whim - he didn't believe the invitation would be accepted - he invited the President and first lady last year to a lavish celebration of Bastille Day. Now he has been rewarded with a full state dinner, plus lots of other honours, including more hand-holding, even laughing off a classic Trump dominance gesture: an attempt to brush dandruff off his suit.
Yet instead of following this obsequious behaviour with an obsequious request, Macron made a speech - using lots of flattering language and lavish references to American history - directly attacking the worldview of Trump.
He called for greater efforts on climate change - because "there is no planet B" - as well as "a more effective, accountable, and results-oriented multilateralism."
He wasn't even subtle in his attack on Trump's backward-looking nostalgia and xenophobic language: "We can choose isolationism, withdrawal and nationalism . . . but that will only inflame the fears of our citizens." And, of course, he supported the Iran deal, which Trump has railed against as recently as this week.
This combination - flattery plus direct talk - hasn't yet been tried on Trump. The friendly gestures will appeal to his narcissism; there is a slim chance - very, very slim - that it might even get him to change his mind about some things. There is a greater risk that the clear opposition, even cloaked in elaborate references to Lincoln and both Roosevelts, might irk him.
But the most likely result is that the American President won't pay attention to what Macron was trying to say - indeed, that he won't even understand that he has been so openly challenged.
And that may have been the point, for Macron's speech will be perfectly understood in France, in Europe, and even in the United States (at least outside the White House).
It thus preserves the French President's dignity in the face of the dandruff incident.
It preserves Europe's aspiration for an alliance with the America described in his speech, the America of Lincoln and both Roosevelts.
It keeps the idea of transatlanticism alive.
And if the President can't hear any of that - because Trump's interest in gestures and power games outweighs his interest in words - then maybe, given the circumstances, that's okay, too.
