On an evening during which he attacked the news media and the judges who ruled against his travel ban, Mr Trump used his speech to talk about migration in Europe and linked it to terror attacks in Brussels, Nice and Paris - before inexplicably adding Sweden to the list.
Mr Trump told supporters in Melbourne: "We've got to keep our country safe. You look at what's happening in Germany, you look at what's happening last night in Sweden.
"Sweden, who would believe this. Sweden. They took in large numbers. They're having problems like they never thought possible. You look at what's happening in Brussels. You look at what's happening all over the world. Take a look at Nice. Take a look at Paris."
One of the country's official Twitter accounts, controlled by a different citizen each week, reacted with bafflement.
Its current administrator, a school librarian, said: "Nothing has happened here in Sweden. There has not [been] any terrorist attacks here. At all."
What Mr Trump's remark referred to in unclear, but it came after Fox News aired an interview with filmmaker Ami Horowitz, whose latest documentary examines whether high crime rates in areas of the country is attributable to its previous open-door migration policy.
The President promised new action on immigration in the coming days. "We don’t give up. We will never give up. We have a court we disagree with," he said, making remarks about the judiciary similar to those his supreme court nominee, Neil Gorsuch, had called "disheartening" and "demoralising" only a week before.
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