What action should be taken to maintain the telescopic sight of the MK 153 SMAW?

Maintaining the telescopic sight of the MK 153 SMAW is essential for ensuring its functionality and accuracy. Using a mild detergent and water provides a safe and effective way to clean the lens and other components without causing damage. Detergents specifically designed for optical equipment can remove dirt and grime while being gentle enough not to scratch or harm the optical surfaces. This method helps keep the sight clear and reduces the risk of obstruction that could compromise aiming and firing accuracy.

In contrast, using oil could lead to smearing on the lenses, affecting visibility and clarity. Alcohol alone may not adequately remove all contaminants and could potentially damage seals or coatings on the optical surfaces if it's not suitable for optical maintenance. Neglecting to clean the sight can lead to a buildup of debris and dust, compromising sight effectiveness over time. Thus, utilizing a mild detergent and water is the most appropriate action for optimal maintenance of the optical sight.