Which is complete bullshit. There is only one combat role you could actually ban women from in terms of biology and that is fighter pilot because of womb displacement or whatever but for the rest it is complete bullshit.
Everyone always cites the muscle mass thing. This can be removed by adequate physical training to a standard that is more than acceptable for a female soldier to serve on the front lines.
And being a combat-effective soldier these days doesn't mean the fittest wins. That has long since passed. IF you'd actually read into the material of the requirements of a modern soldier, especially in the counter-insurgency scheme, you'd hear terms such as 'strategic corporal, warrior-diplomat". Especially within the US armed forces a lot of firefights and all-out clusterfucks in urban environments were caused by disproportional use of violence to even non-violent situations. So much for hearts and minds. The on average different mindset of women and them being less aggressive in nature counts for more than sheer muscle mass.
Oh and btw, being in the infantry is suprisingly less demanding than people think. The biggest amount of physical strain in the long run in the infantry is carrying a heavy backpack for ugh amount of kilometres and even that is usually taken away by the presence of motorised vehicles. FIghting is strenuous but you aren't going to tell me the absolute worst (72-hour firefights) is something anyone can actually prepare for. That is a mental thing, much less physical.
I'd say things like air assault infantry (not even close to the largest portion of troops in the infantry) and recon positions are much more strenuous. Special forces is another thing entirely but it's an exception that can be ignored on the subject.
That being said, the combat role "because women don't have the strength to fight" has long since been proven to not be true. In Afghanistan and Iraq, supply troops were the units to be attacked the most and had some pretty fucking badass firefights. In fact, there are a lot of Female marine POGS with a supply MOS who have been under fire more than male marine grunts.
Oh and comabt roles in general is a wrong term to use, because you'd imply that women also wouldn't be able to drive tanks, fly attack helicopters and fly drones.
In general a defense organisation profits hugely if the organisation is diverse. With a homogenuous group you are comitting intellectual incest and your armed forces, esepecially on the intellectual side, need different world views, perspectives and opinions in order to be able to handle all the kinds of complex trasks there are.
Saying women for biological reasons as a generalistation should be forbidden to perform combat roles is just a retarded as saying skinny people won't be able to carry a heavy backpack and thus shouldnt perform combat roles and saying fat people cant fight because they're too slow.