In what will hopefully be the first of many studies to yield similar conclusions, researchers at the Michael D. Palm Center of the University of California at Santa Barbara have found no significant difference in performance between armed forces units allowing LGBT individuals to serve openly and those endorsing a "don't ask, don't tell" policy. Headed by four retired US military generals of varying political attitudes, the study assessed combat performance of different batallions on a number of dimensions. This article from the Associated Press gives a good summary of the study and provides basic background on its principal investigators.
The issue of "unit cohesion" is difficult to address with quantitative methodology, so researchers in this study turned instead to more straightforward indicators of combat performance. Skeptics still question the weight of this evidence, and make a valid point in saying it is difficult to collect empirical data on the impact of social attitudes, but the use of performance measures to address the issue of sexual orientation's impact in a scientific manner constitutes an important step forward in and of itself. Analyzing the impact of sexual orientation and DADT on military service units from a scientific perspective removes the issue from the realm of morality and stigma, and places it into the realm of intellectual inquiry and performance optimization.
Many high-ranking officials in the US military have also begun to see how the DADT policy can actually exert a negative impact on cohesion among members of a unit. As some of the current officials interviewed in the article suggest, the atmosphere of secrecy and dissemblance wrought by DADT creates a sense of unease and distance among members of military batallions, and can prevent troops from bonding with one another the way they could in a more open social structure such as that found in the British or Israeli military. With more military servicepeople than ever before surviving severe traumatic injuries and/or incurring significant psychological trauma from combat, these bonds constitute a vital component of the support system available to servicepeople in crisis.
Hopefully more military analysts will take up the mantle of open inquiry into the true impact of sexual orientation disclosure policies, and use these findings to advocate for legislation that creates a more open and supportive environment for all those who risk their lives in combat on behalf of the United States. Regardless of whether or not one supports the current armed conflicts in Iraq and Afghanistan, the individuals serving there are working hard on a daily basis to restore infrastructure and stability in badly fractured societies, and deserve the most nurturing and accommodating social fabric possible to sustain them psychologically through times of tremendous darkness and frustration.
Moreover, if one does believe in sowing the seeds of democratic participation in other societies, surely the best place to start lies just as much in the demonstration of one's own country's commitment to true openness and equality for all residents as it does in the building of roads or the removal of landmines. Setting an example of inclusion and open-mindedness certainly constitutes a vital component of any long-term strategy for encouraging people in other countries to exercise political self-determination, whether through representative democracy or through an alternative paradigm of their own choosing.