At a press conference on national security that followed the massacre of 49 people in Orlando, Florida, Donald Trump announced that he would suspend immigration from countries with a "proven history of terrorism".
In a section of the speech that attacked Hillary Clinton's refugee policy Mr Trump said:
When I’m elected, I will suspend immigration from areas of the world where there is a proven history of terrorism against the United States, Europe or our allies until we fully understand how to end these threats.
His hectoring approach to immigration and his attempt to associate refugees with the terrorism that they themselves are fleeing has proven to be a crowd pleaser at rallies.
People have been quick to point out that this "policy" is so ill conceived it would be funny if he weren't within reach of the Presidency.
For instance, it's quite difficult to pin down exactly what constitutes a country having a "history of terrorism". People have taken to the internet to point out this misunderstanding of how the world actually works.
Immigration from Britain to America would stop under Mr Trump's definition.
Three out of the four men convicted of the 7/7 bombings, an attack on one of America's allies, were born in Leeds and the fourth had moved to Britain at the age of five.
The Brighton Bombing in 1984 in which members of the IRA attempted to assassinate Margaret Thatcher and in the process killed five senior members of the Conservative Party and injured 31 others, is another example. The man convicted of this was Patrick Magee, a British Citizen from Belfast.
The Gunpowder Plot is probably the most insurmountable barrier to Brits entering America. Terrorism doesn't get much more historical, and Guy Fawkes was a lad from Yorkshire. As is well known Guy was of course "radicalized" and took on the holy warrior name "Guido" (Which in Catholic means...Guy) when he went to Spain.
Dan Kaszeta, a veteran of the US Army's Chemical Corps and a security specialist provided this succinct analysis:
Previously Mayor of London Sadiq Khan declined to be exempted from Mr Trump's plan to ban all Muslims from entering the United States. Will the Republican candidate be forced into offering another exception, this time to the whole country? To all of Europe and America's allies?