KLM cancellation policy 24 hrs applies to all flights to / from the US This is in line with the US Department of Transportation's policy for all flights to and from the US.

KLM's flexibility service options allow lightweight or standard ticket owners to:
You can change your flight up to 3 times, up to 48 hours before departure, at no additional charge.
Change the date, time, and / or destination of your trip within Europe at no additional charge.