United States authorities have tightened airline security after intelligence reports suggesting terrorists could use thermos-style flasks to hide explosives.
Travellers are being warned to expect greater scrutiny of insulated drinks containers, the ABc reports.
The US Transportation Security Administration says there is no specific threat, but it will pay closer attention to such containers because of new information about possible terrorist tactics.
Liquids are already restricted, but the new measures apply to empty drink bottles as well.
Passengers are still allowed to carry them onto planes, but will face additional screening.
It is a sensitive time in the United States. Last Christmas Day a Nigerian man allegedly tried to blow up explosives sewn into his underwear aboard a plane bound for Detroit.