Some airports sell beverages after security, then prohibit taking them on the plane. Mexico and South Korea have both done this to me. They then offer to sell m

Some airports sell beverages after security, then prohibit taking them on the plane. Mexico and South Korea have both done this to me. They then offer to sell more beverages on the plane. A pure racket. In the US, large amounts of liquid are not allowed through security. But frozen liquid is allowed. I am not making this up. Just make sure your liquid is frozen enough to be solid as you clear security, and thawed enough to drink on the plane.