The difference between “Islamic extremism” and “Islamist extremism”? One exhausted President.

President Donald Trump’s substitution of the slightly different terms during his highly anticipated speech in Saudi Arabia on Sunday might go unnoticed by the average US listener.

But the subtle change — or slip, as the White House called it — could mean the difference between offending Middle Eastern allies and not, a concern for any president looking to create a good first impression with a key ally on a first trip abroad.

Using the word “Islamic,” a reference to the religion, in the same breath as “terrorism” could be seen by Muslims as an affront to their faith and actually play into the terrorists’ “clash of civilizations” narrative — reasons why President Barack Obama assiduously avoided the combination during his presidency.