As Prime Minister Justin Trudeau of Canada made his first address to the United Nations General Assembly on Tuesday, he spoke before not only an enthusiastic audience, but one whose agenda largely mirrored his own.

Two hallmarks of Mr. Trudeau’s government since it took power 10 months ago have been admitting Syrian refugees and promising action on climate change.

While he raised both of those issues in his speech on Tuesday, Mr. Trudeau also used the occasion to underscore another two of his favorite themes: optimism and internationalism.

“We need to focus on what brings us together, not what divides us,” Mr. Trudeau said. “For Canada that means re-engaging in global affairs.”