I was in the packed hall at Davos to hear Trump speak. The audience went from laughter to silence in seconds.

Trump took the stage virtually at this year’s World Economic Forum in Davos.

Spriha Srivastava/Business Insider.

Donald Trump addressed the World Economic Forum at Davos Thursday.BI’s Spriha Srivastava was in the room where CEOs and leaders listened to him speak.They laughed but also sat silent as he bashed the EU and indulged in his campaign-trail rhetoric.

If you didn’t know President Donald Trump had taken the oath of office three days before, you might have thought his speech at Davos’ Congress Hall was a campaign event.

Trump’s virtual address on Thursday afternoon drew a massive crowd, with people lining up outside the 700-seater hall.

As he was introduced, the room erupted in applause. Trump began by congratulating the World Economic Forum on organizing the conference, but he quickly pivoted to his signature “America First” rhetoric. When he discussed limiting “transgender surgeries,” a few people around me sighed in disappointment.

A panel of top CEOs from around the world posed questions. When Blackstone CEO Steve Schwarzman asked about Europe, Trump didn’t hold back, voicing his frustration with European regulations. His remarks left many European leaders in the audience stone-faced. The room was silent. Frustration over European regulations has been a recurring theme this year — perhaps Trump’s blunt message made that even clearer.

The mood lightened when Trump joked about offering Canada the chance to become the 51st state, prompting laughter across the room. “He has a way of keeping the crowd engaged,” the person next to me said.

The line outside the hall to hear Trump’s speech.

Spriha Srivastava/Business Insider

The audience laughed when Trump corrected WEF president Børge Brende, telling him that China’s President XI had phoned him, and not the other way round.

But one of the biggest moments came when Ana Botín, executive chairman of Santander, introduced herself by subtly challenging Trump’s familiarity with her. “You may not know me as well as the other panelists,” she said before adding that Santander’s global customer base was actually larger than Bank of America, whose CEO, Brian Moynihan, was onstage with her, or J.P. Morgan. The audience erupted in laughter, and I heard someone whisper, “Go Europe.”

After the speech, a journalist sitting next to me said it was a “missed opportunity” for Trump. “I don’t think he said anything we haven’t heard before but he had a real opportunity to engage with leaders here,” he said.

One delegate, a woman in a dark blue suit, told after she’d left the hall at the “transgender surgeries” remark. “I couldn’t listen to it,” she said.

Trump’s speech reminded me how different his style is from the measured, diplomatic tone that usually defines Davos. Whether his message landed the way he intended, however, is another question.