Emerging digital twin technology is still at the stage of diverse standards and implementations, and its potential has not been widely validated. Digital twins allow systems to be fully digital from design time, even when combined with today's physical systems and can increase efficiency, validate ideas, and provide additional security. Digital twin technology has already highlighted its potential in industries such as construction, manufacturing, automotive, and agriculture. In this paper, the application of digital twin technology to smart airports is discussed, focusing on the physical and cyber security of airport subsystems. The advantages of adopting digital twin systems are discussed and recommendations are provided by sorting out the current cyber threats to smart airports, and countermeasures.