"Study what General Pershing of the United States did to terrorists when caught. There was no more Radical Islamic Terror for 35 years!"

The tweet harked back to Mr Trump's speech on the campaign trail in February 2016. He referenced the supposed actions of General Pershing, and suggested them as a blueprint for how terrorists should be treated.

The only problem was that no historians believe the US general did what Mr Trump claimed.

The president said that, during the Moro rebellion in the Philippines between 1901 and 1913, General John Pershing executed Muslim insurgents with bullets dipped in pig's blood.

Critics called it apocryphal, misleading or outright false.

The fact-checking website Snopes considered the evidence and called it a "legend", while Politifact rated it "pants on fire".