DAVOS, Switzerland — When President Trump arrived on Thursday at the conference center where the world’s financial and political elite have been meeting, onlookers crowded a balcony and craned their heads to see the leader who has challenged the very international order that Davos represents. At first, it was quiet. Then someone called out a question.

“Are you going to be treated well?” he was asked.

“You tell me,” Mr. Trump replied.

The reverse question was unasked but hung in the air: How was he going to treat them?

If he was not exactly entering the lion’s den, it was nonetheless a fraught moment for both sides as the America First president ventured into the lair of the we-are-the-world banking titans, corporate magnates and international leaders who have spent decades preaching the virtues of global integration.

Rather than confrontation, both sides labored for conciliation, at least to a point. For one afternoon and evening, at least, Mr. Trump threw no protectionist grenades and even broached the possibility, however remote, that he would re-enter a Pacific trade agreement that he scrapped last year, if it were renegotiated. For its part, the Davos crowd welcomed its top critic with a reception and warm words.