As The Washington Post's Philip Bump puts it, Johnson's response was like "if the Titanic had begun sinking but then blew up."
But presidential candidates are not the only people confused about Aleppo. In a subsequent MSNBC interview, Christopher Hill, a former U.S. ambassador to Iraq, described the city as the "capital of ISIS," an alternative name for the Islamic State, an error also included in some media reports. Aleppo is not considered the capital of the self-described Islamic State — that would be Raqqa.
You can test your own geographic knowledge of the situation below.
For those who don't know what it is, Aleppo is a city in Syria. Before the war it was the largest city in the country, well known for its historical sites and great food. Since the war the city has been decimated by fighting. During the past few months, the city has come under siege from various forces, prompting a huge humanitarian crisis.
On Tuesday, the Syrian government dropped a bomb containing chlorine on one besieged neighborhood.