On Tuesday morning, the Department of Homeland Security announced new restrictions for personal electronics on direct flights to the U.S. from 10 airports in the Middle East and North Africa. Devices larger than a cellphone will not be allowed in the cabin, though they will be allowed in checked baggage.
Later Tuesday, the U.K. announced it would be enforcing a similar rule — using a slightly different list of countries.
The rule change in both countries was unexpected and the explanations for it cryptic.
Here's a quick look at what we know, and what we don't.