It may require making some changes especially in attitudes but I doubt it will cause (many) problems.
This issue with (problems) was also used for resisting allowing blacks and other minorities, along with women to be considered for military duty.
The U.S. has never led when it comes to making changes like this. Eighteen countries currently allow transgender people to serve in their military. They are: Australia, Austria, Belgium, Bolivia, Canada, Czech Republic, Denmark, Estonia, Finland, France, Germany, Israel, Netherlands, New Zealand, Norway, Spain, Sweden, and the United Kingdom.
I'm sure if they were able to pull it off so can we. Having said that it does not mean there will not be issues of discrimination among the rank and file.
A 2012 Pentagon survey found that approximately 26,000 women and men were sexually assaulted. Of those, only 3,374 cases were reported. In 2013, a new Pentagon report found that 5,061 troops reported cases of assault. The belief is people are becoming more comfortable with coming forward to report incidences.