The authoratative source on this issue is Phyllis Schlafly, in my opinion. She has a way of saying the true things that people, especially many women, do not want to hear. The truth of the matter is, men and women are not equals, physically or biologically. Period. End of story. Anyone who argues otherwise is simply being either blind or politically correct. This is not to argue that women are not mentally as tough or capable as men, because that is beyond argument. But women in general cannot put an 80 pound pack and trudge around in the mountains of Afghanistan. Some can, but the average woman has no chance, only the exceptional top fraction could even consider it. But that is not the real isssue. The real issue is to deny biology, which is what many liberals and feminists want to do (I know, redundancy). If a woman CAN get pregnant, there is always a possibility she WILL get pregnant. And the impact that can have on force readiness is well documented. To insist that pregnancy is something that can be simply avoided is just plain STUPID. If you put men and women in close proximity under trying/dangerous/boring conditions, pregnancy can result. An example of how this can negatively impact operational readiness is the Submarine Example. Many feminists and democrats want to put women on submarines. If a woman gets pregnant (and a sub would be a fine crucible for sexual activity, boredom, close quarters, etc.) a pregnant woman would have to be removed from the submarine as soon as any pregnancy is detected. There are trace elements in the recirculated submarine atmosphere that are not harmful to a fully developed adult, but are toxic to a developing fetus. That billion dollar weapon platform whose job is to remain undetected and invisible, would need to surface to transfer the woman off the vessel ASAP, a dangerous task under the best of conditions, compromising the mission. This is one example. Like it or not, it is the truth.
You make a good point. Out of approximately 100 men I went through basic training with there were a handful, approximately 5, who couldn't physically cut it. I wonder how many women out of a random 100 would not make it under the same training conditions. I venture to say it would be closer to half. What's more, when I got to Vietnam the conditions were much worse than in basic, with rucksacks and ammo routinely weighing 50 pounds or more, horrendous sanitary conditions, skin problems of every sort, and living conditions which were hardship for even the most rugged individual. While there is no doubt there are some women who can handle all these conditions, they are in a minority and if we had to institute a draft it would skew the number of combat ready forces dramatically. These issues don't even begin to address the psychological and cultural issues which make a tight band of men a good fighting force, and one that would be crippled with the introduction of a woman.