U.S. Special Forces in Afghanistan - as depicted in the movie 12 Strong - adopted beards and longer hair to better blend with and be accepted by local leaders and populations. In a time of rising terrorist activity, changing hair and shaving regulations for all male service members would reduce their chances of being singled out as targets while off duty.
Walk through any airport around the globe and you could, without much difficulty, point out almost every male U.S. armed forces service member by his haircut and clean shaven face. In the wake of 9/11 and increased terrorist activity, those easily identifiable personnel are now potential targets. Bringing back beards and changing the hair length regulation would allow our personnel to blend in with the rest of the population.