According to the 2026 TSA and international security guidelines, you can take ice cubes through security only if they are completely frozen solid at the time of screening. If there is any liquid water at the bottom of the container, the ice is treated as a "liquid" and must adhere to the 100ml (3.4 oz) rule, which usually leads to confiscation. This is known as the "Solid State Rule." To successfully pass, many travelers use high-quality vacuum-insulated flasks and fill them with ice just before leaving for the airport, ensuring no melting occurs during the commute. Once you are past the checkpoint, you can fill the rest of the flask with water from a fountain. Security officers may occasionally perform an additional "swab" test on the container to ensure the contents are indeed just water, so it is best to use a clear container if possible to make the visual inspection faster and more straightforward.