The "Don't Ask, Don't Tell" policy that bans openly gay men and women from serving in the United States military should be repealed immediately. Many countries, including Israel, allow gays to serve openly in their armed forces and no harm is done.
The main argument made by supporters of the current policy is that changing the regulations would hurt unit cohesion. In other words, homophobic soldiers won't feel comfortable around homosexuals who are out of the closet. Well, it's easy to check if American soldiers are less open-minded than Canadian and European soldiers. Many Americans already serve with openly gay foreign soldiers, as part of NATO and other international forces. How are the relationships between American soldiers and their gay counterparts? It wouldn't take too long to conduct such a study.
Obviously, there will be problems here and there with homophobic incidents, but on the whole, acceptance of gays will probably go smoothly.