The Daily Mail (UK) reports that “an elite group of special forces silently race across enemy lines on stealth motorcycles that fighters would never suspect were coming.”  

“That’s the scenario the US military is hoping for with its development of the ‘Silent Hawk’ – a hybrid engine dirt bike for use in reconnaissance missions.”  

“The idea is that for normal operations, the bike would use diesel, gasoline or jet fuel. But when it gets closer to the enemy, it would run almost silently on electricity.”