With a pair of weekend retweets, President Donald Trump amplified another unfounded conspiracy theory.
It was hardly the first time. His political career began the same way. While birtherism was Trump's most infamous conspiracy theory, it was far from his only one.
He has promoted dozens of outlandish claims, many of which are so blatantly untrue that they have not required even a cursory fact check to disprove.
Among his claims:
That President Barack Obama wasn't born in the U.S.
President Donald Trump has a long history of spreading falsehoods drawn from the conservative fringe. His unlikely rise to the White House was fueled in part by spreading the lie that President Barack Obama was not born in the U.S.
Even after Obama produced his long-form birth certificate that proved he was born in Hawaii, Trump repeatedly voiced the belief, only fully backing off in the final stages of the 2016 campaign.
An 'extremely credible source' has called my office and told me that @BarackObama's birth certificate is a fraud.— Donald J. Trump (@realDonaldTrump) August 6, 2012
Always remember, I was the one who got Obama to release his birth certificate, or whatever that was! Hilary couldn't, McCain couldn't.— Donald J. Trump (@realDonaldTrump) June 29, 2014
In 2015, he tweeted that Hillary Clinton had actually started the "birther movement."
Just remember, the birther movement was started by Hillary Clinton in 2008. She was all in!— Donald J. Trump (@realDonaldTrump) September 23, 2015
That the Clintons are involved in Jeffrey Epstein's death.
Most recently, Trump has used the power of the presidency to promote a baseless claim about the death of disgraced financier Jeffrey Epstein, breaking another norm of the office and further sowing public confusion over the apparent suicide of one of the most high-profile inmates in the federal system. Epstein, who faced up to 45 years in prison on federal sex trafficking and conspiracy charges, was found dead in his cell in a Manhattan jail early Saturday.
Epstein had ties to prominent people around the globe, including Trump, who partied with him in the 2000s, and former President Bill Clinton. Within hours of Epstein's apparent suicide, Trump retweeted an accusation that tied both Bill and Hillary Clinton to the death, one of many conspiracies circulating on social media. Trump defeated Hillary Clinton in the 2016 election.
Died of SUICIDE on 24/7 SUICIDE WATCH ? Yeah right! How does that happen#JefferyEpstein had information on Bill Clinton & now he’s deadI see #TrumpBodyCount trending but we know who did this! RT if you’re not Surprised#EpsteinSuicide #ClintonBodyCount #ClintonCrimeFamily pic.twitter.com/Y9tGAWaAxX— Terrence K. Williams (@w_terrence) August 10, 2019
Trump defended the retweet on Tuesday, calling the original poster "a very respected conservative." He said he had "no idea" whether the Clintons were involved in the death, but continued to fan the theory, saying that the former president spent far more time on Epstein's private plane, and perhaps his private island, than known.
The Clintons have denied any wrongdoing. In a statement last month, Clinton spokesman Angel Ureña said the former president took four trips —one to Asia, one to Europe and two to Africa — on Epstein's airplane in 2002 and 2003. Staff and Secret Service detail traveled with Clinton on "every leg of every trip," Urena said.
Ureña also said Clinton had never traveled to Epstein's private island.
Trump has made a similar accusation before: that the Clintons had a hand in a high-profile suicide. He previously tweeted about the 1993 death of White House aide Vince Foster, calling it "very fishy." But there is no evidence of foul play.
That Sen. Ted Cruz's father may have had a hand in President John F. Kennedy's assassination.
During the 2016 election, Trump said during a Fox News interview that Ted Cruz's father, Rafael Cruz, was with Lee Harvey Oswald before Kennedy was shot.
"What was he doing with Lee Harvey Oswald shortly before the death, before the shooting? It's horrible."
The theory was fueled in part by the National Enquirer, which published a photo that it claims shows Rafael Cruz with Oswald handing out pro-Fidel Castro pamphlets.
Ted Cruz has denied the allegations.
"Yes, my dad killed JFK, he is secretly Elvis and Jimmy Hoffa is buried in his backyard," he joked during a 2016 interview.
That Supreme Court Justice Antonin Scalia may have been murdered.
Supreme Court Justice Antonin Scalia died unexpectedly in 2016 during a hunting trip in Texas. Then-presidential candidate Trump questioned the manner of his death during in interview with radio talk show host Michael Savage.
"I just landed and I’m hearing it’s a big topic," Trump said. "But they say they found a pillow on his face, which is a pretty unusual place to find a pillow."
He later fueled rumors that Obama is Muslim by questioning his motives for not attending Scalia's funeral.
I wonder if President Obama would have attended the funeral of Justice Scalia if it were held in a Mosque? Very sad that he did not go!— Donald J. Trump (@realDonaldTrump) February 20, 2016
That thousands of Muslims celebrated in U.S. cities after the Sept. 11, 2001, terror attacks.
Trump claimed several times during his 2016 campaign that he saw "thousands and thousands" of people celebrating after the 9/11 terror attacks.
"I watched when the World Trade Center came tumbling down. And I watched in Jersey City, New Jersey, where thousands and thousands of people were cheering as that building was coming down," Trump said during a rally.
Although Trump said news of the celebration "was well covered at the time," several news agencies have debunked the claim.
Trump defended his statements by tweeting a video clip of WABC-FM radio host Curtis Sliwa talking about the celebrations. Silwa said the clips were taken out of context and that a caller had mentioned dozens — not thousands — of teenagers celebrating.
That 3 million to 5 million votes were cast illegally in the 2016 election, none of them for Trump.
Trump claimed that anywhere from 3 million to 5 million votes were cast illegally in the 2016 election.
In addition to winning the Electoral College in a landslide, I won the popular vote if you deduct the millions of people who voted illegally— Donald J. Trump (@realDonaldTrump) November 27, 2016
He continued his voter fraud theory in January after the 2018 midterm elections.
58,000 non-citizens voted in Texas, with 95,000 non-citizens registered to vote. These numbers are just the tip of the iceberg. All over the country, especially in California, voter fraud is rampant. Must be stopped. Strong voter ID! @foxandfriends— Donald J. Trump (@realDonaldTrump) January 27, 2019
That vaccines may cause autism.
Trump has long fueled misconceptions that vaccines are linked to autism, such as with this tweet from 2014.
Healthy young child goes to doctor, gets pumped with massive shot of many vaccines, doesn't feel good and changes - AUTISM. Many such cases!— Donald J. Trump (@realDonaldTrump) March 28, 2014
He continued the claim during a Republican debate in 2015.
"You take this little beautiful baby, and you pump — I mean, it looks just like it is meant for a horse, not for a child, and we had so many instances, people that work for me, just the other day, 2 years old, beautiful child went to have the vaccine and came back and a week later got a tremendous fever, got very, very sick, now is autistic," he said.
Trump had also told similar anecdotes in previous interviews.
The claims come from a since-debunked 1998 study that showed the mumps-measles-rubella vaccine was linked to autism.
Trump has since changed his public opinion and, as of April 2019, has encouraged parents to fully vaccinate their children.
That global warming is a hoax perpetrated by the Chinese.
Trump has long questioned the validity of climate change, something that more than 97% of actively publishing climate scientists agree on, according to NASA. He's even gone as far to say that it's a hoax perpetuated by the Chinese.
The concept of global warming was created by and for the Chinese in order to make U.S. manufacturing non-competitive.— Donald J. Trump (@realDonaldTrump) November 6, 2012
When asked in November 2018 about a climate report released by the U.S. government, Trump told reporters, "I don't believe it."
That wind farms may cause cancer.
In 2012, Trump openly opposed the development of an offshore wind farm near his luxury golf course in Aberdeenshire, Scotland. He called the wind turbines "ugly monstrosities."
Trump continued his attack on wind farms earlier this year at an April 2 fundraiser for National Republican Congressional Committee.
"If you have a windmill anywhere near your house, congratulations, your house just went down 75 percent in value," Trump said. "And they say the noise causes cancer."
No studies have supported the claim that wind turbines cause cancer, according to Politifact.
The impact of presidential conspiracy theories
With the weight of the Oval Office behind these claims — some containing deliberate misinformation, others ignorance — the theories carry a degree of peril, according to presidential historian Julian Zelizer.
"We expect some semblance of truth from the Oval Office and sending out conspiracy theories like this is a whole new level of danger," Zelizer, a history professor at Princeton University. "People believe some of this, people can act on some of this. People can act violently, even, and part of that comes from a president dealing in untruths and conspiracies."
For his part, Trump sometimes says that a mere retweet absolves him of any responsibility.
Repeatedly, he claimed he was just passing on information to his Twitter followers — now over 63 million — while not recognizing the significance carried by words, distributed in any fashion, by the president of the United States or leader of the Republican Party. During the 2016 campaign, in just one example, Trump retweeted false crime statistics that dramatically overstated the number of white people killed by black people.
"Bill, am I gonna check every statistic?" he told Fox News host Bill O'Reilly then. "All it was is a retweet. It wasn't from me."