Donald Trump's reactions can be extremely unpredictable at the best of times.
But his reaction to the terror attack in Barcelona was to reference a myth involving pig's blood and an American general.
After he stated the US would give its full support to Spain, this is what he posted on Twitter:
This isn't the first time he's mentioned General Pershing, who commanded American forces on the Western Front in the First World War.
During his campaign, he continually referenced a story of how the general had Muslim prisoners executed by bullets coated in the blood of pigs in order to deter uprisings against US rule.
A fact-checker - Snopes.com - later proved this story was false, but it was still mentioned at the then-candidate's rallies.
Trump's former campaign manager, Cory Lewandowski, later admitted he and other members of the group knew the story was false, but told The Washington Post it didn't matter because it was "an analogy."
Lewandowski was later fired from the Trump campaign, although it is unclear whether it was for this reason.