It all began at a rally in Melbourne, Florida, Donald Trump's first political rally as president.
After telling the crowd about the need to keep America safe, he went on to leave many confused.
"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."
He continued on to refer to terrorist attacks in other cities around the world.
"You look at what's happening all over the world. Take a look at Nice. Take a look at Paris. We've allowed thousands and thousands of people into our country, and there was no way to vet those people, there was no documentation, there was no nothing. So we're going to keep our country safe."
But with no immigration-linked terrorism nor security incident reported in Sweden, many Swedes responded on social media.
That included Sweden's former prime minister Carl Bildt, who tweeted:
"Sweden? Terror attack? What has he been smoking? Questions abound."
While many were amused, the Swedish government asked the United States to explain.
The White House responded by saying:
"Mr Trump was talking about rising crime and recent incidents in general in Sweden and was not referring to a specific incident."
And Mr Trump has also now sought to clarify his words, tweeting:
"My statement as to what's happening in Sweden was in reference to a story that was broadcast on Fox News concerning immigrants and Sweden."
Meanwhile, the irony of Mr Trump's apparent gaffe has been highlighted by his continuing criticism of the US media.
In a recent attack on Twitter, he accused the media of being "the enemy of the American people."
Responding to that tweet, US Republican senator John McCain has strongly defended the media.
"If you want to preserve democracy as we know it, you have to have a free and, many times, adversarial press. And without it, I am afraid that we would lose so much of our individual liberties over time. That's how dictators get started."
His comments also come days after Mr Trump repeatedly criticised reports of disorder in the White House and leaks of his phone conversations with the leaders of Mexico and Australia.
Mr Trump has become known for his accusations against specific media outlets, calling them "fake news outlets."
That seeming disdain for the media has started people comparing him with former US president Richard Nixon.
Mr Nixon was once privately recorded saying, "The press is the enemy."
Carl Bernstein, the former Washington Post reporter who helped uncover the Watergate scandal, has told CNN Mr Trump's words amount to a demagogue's statement.
"Trump's attacks on the American press as 'enemies of the American people' are more treacherous than Richard Nixon's attacks on the press. Nixon's attacks on the press were largely in private. There's a history of what 'enemy of the people,' that phrase, means as used by dictators and authoritarians, including Stalin, including Hitler."
White House Chief of Staff Reince Priebus has defended Mr Trump's rhetoric to Fox News.
"You should be concerned about mainstream news outlets that are acting like, you know, Washington daily gossip magazines, instead of the way it used to be where you'd get a few sources on the record -- yeah, you'll need some background, and, yes, maybe you'll need some anonymous sources -- but to accuse an organisation of being in constant contact with Russian spies is outrageous and, every day, it's something different, it's some other source that is absolutely untrue."
