I thought this was an interesting angle, written over a decade ago, even more relevant today:

By and large the less important the role of the military, or individual units, as a warfighting machine the more they are penetrated by women. If only because research shows that going into combat is the last thing most military women want, the more of them there are around the less capable those military are of acting as effective combative units. And indeed the one military which has gone furthest down the road—i.e., the American one—is now paying a heavy penalty for the folly of the responsible politicians and voters as cohesion suffers, training becomes almost impossible, and some of its best personnel are forced out by ‘sexual harassment’ claims which may or may not be well founded. No wonder that, as of late 1999, all except the US Marines, which only have about half as many women as the rest and who are the only ones to insist on separate basic training, were unable to meet their recruitment targets.

http://www.libreriamilitareares.it/BIBLIOTECA/BIBLIOTECA%20MILITARE%20DIGITALE/I.%20TRATTATI%20MILITARI/TRATTATI%20ARTE%20DELLA%20GUERRA/VAN%20CREVELD/Great%20Illusion%20Women%20in%20Military.pdf