Cities are certainly a different type of problem for armies geared to open ground warfare. And megacities (defined as at least 10 million inhabitants) are obviously a bigger problem. But I don't like this idea:
[Despite] the clear recognition that armed forces will increasingly be required to fight in urban areas, no army has committed to train, organize, and equip forces specifically to operate in cities. It is time for the US Army to do just that.
I say no. My view is that any good soldier can do any job:
Remember that we did turn soldiers trained for high-intensity warfare into counter-insurgents very smoothly in Iraq once the officers and doctrine were there to guide the soldiers. Counter-insurgency--as any other military operation--requires good soldiers. And the speed of high-intensity combat means that it is far safer to prepare for that mission while being ready to adapt to an insurgency. That's what I wrote about here.
If megacities are a problem--and they are--we need doctrine to fight in them and officers well versed in that doctrine. Have that and, as we did in Iraq with counter-insurgency, we can fight and win in megacities.
Remember, these are megacities. They are huge. Hence "mega." Why would creating a 5,000-man unit specialized in fighting in that huge environment do any good? Isn't that like peeing in the ocean and expecting the water level to rise? A 5,000-man unit will be useless in non-urban environments yet not nearly large enough to win a fight in a megacity.
So don't create Army units specialized in urban warfare in megacities.
But perhaps the Marines could more easily adapt to that job as I wrote back in 2000 (see page 38):
The Marine Corps is already light and has more flexibility to adapt to new strategic realities. It must abandon amphibious warfare as a core capability and embrace an expeditionary role based on urban warfare and air mobility to complement the role of the Army to fight heavy forces.
The Marines have the advantage of being trained and focused on seizing defended targets in essentially a frontal assault after crawling out the sea. Seizing defended cities without getting their feet wet might seem easy by comparison.
So adding megacities to the Marine skill set doesn't seem to detract from their amphibious assault role.
And unlike amphibious assault which may not be possible on a large scale any more--and which the Navy can't carry out with the available amphibious warfare assets anyway--battles for megacities will allow Marines to commit a larger force to the fight.
The Army can certainly work on adding this skill set with engineer units trained and equipped for urban warfare as part of their skill set to help Army units committed to the fight.
And if Army units are earmarked for a city battle, of course they should receive extra training prior to the mission--just as any mission requires training for that mission.
Well-trained Army soldiers, doctrine, and officers who know how to use good soldiers and combat engineers trained and equipped to keep soldiers moving through a city will be a far better solution than creating a small Army unit dedicated to that mission.
But I'm biased for general purpose Army forces. Years ago I argued against a constabulary force carved out of the Army force structure for peace operations. I reprinted a 1998 letter on my original site that still lives here that Army magazine published on their then online supplement to their September 1998 issue (I'd forgotten about that. I guess writing this post triggered a memory!).