If you want to picture the characteristically 21st century living environment, imagine cities like Lagos and Shanghai; or Sao Paulo, New York and Cairo. Now double the population, and you have a pretty close approximation of what the world’s largest urban areas will be like by mid-century.
Now ask: How does the Army control a city of that size? How does an infantry force of thousands cut off and surround and city of 10 million? What about 20 or 30 million? The answer is that the United States can’t, at least not yet.
I know JTHipster was kidding in his comment, but he mentioned collateral damage and it was the first thing I was thinking of. In WW2, the bombings of Dresden, Hamburg, Tokyo, London, and Hiroshima/Nagasaki were operations-- at that time--in the era's megacities relative to New York and Sao Paolo today. In fact some of those cities still are megacities today, and I think it's worth taking a serious consideration of why we wouldn't just firebomb or MOAB a city we're at war with, as we so proudly did then. Wait. I know it sounds ridiculous, it probably is. But look, at present, we're either fighting guerilla-style enemies in the Middle East or tangoing with individual wildcards like DPRK and Iran. I think this article, and apparently that Strategic Studies Group, is considering military operations in megacities as a combination or similar style as today's aforementioned operations, and that's a fatal fantasy to be dreaming. Now, unless we're hunting another Escobar, or fighting those ad-hoc militias that run the streets of corrupted cities like Sao Paolo, a war in a megacity would be a war, it would mean those cities of tens of millions have stumbled into something nasty and we're trying to neutralize something a LOT bigger than a cartel. In which case, I'd like to see if we really wouldn't be pulling another "it's for the greater good!" as we burn that megacity to the ground. Otherwise, we wouldn't be doubting the capabilities of the U.S. military. We wouldn't have to question if we can handle deploying a force "large enough" for an operation in a megacity to depose insurgents or cartel, cause we already know we damn well have it.
Guided ordinance substantially changed warfare. We bombed the bejeesus out of Dresden et. al. because we had no capacity for targeted bombing. Think on it - the Japanese would never have undertaken Kamakaze warfare if they had guided missiles. The development of targeted weaponry basically birthed modern American military doctrine. Without it, you have no asymmetrical warfare. With it, I've got satellite maps, UCAVs, covert ops, standoff weaponry, the whole nine yards. As such, the conventional approach to taking a city is 1) cripple it via special forces and targeted aerial strikes 2) overrun it to take advantage of confusion 3) corral its supply lines to limit resupply 4) divide and conquer through quadrants until you've pacified the whole thing The illustration of the paper linked is that you're never going to overrun Lagos and if you can't overrun it, you can't corral it. It doesn't matter how asymmetrical your military advantage is, you just don't have the numbers. It isn't militarily advantageous to flatten the civilian population. In an ideal battle you leave the civilian infrastructure intact and unharmed so that you aren't left with insurgent hell. The paper argues that your choices are to dresden the fuck out of your target or relive Blackhawk Down. And that's the real lesson here: modern military doctrine has no capacity for controlling insurgency against a megacity. "Shock and Awe" barely worked against Baghdad at at 6.3 million... which puts it at #51 on the list behind a number of probable targets in the coming years. Call it a war, call it a police action, call it what you will - the bottom line is military strategy is likely to fail against a lot of theaters we might encounter.
Okay you're right, but I honestly still don't see how we don't have the numbers. The U.S. Special Forces has 66,000 active duty personnel; there are over 200,000 active duty Marines with another ~40,000 on reserve. Now I understand they're spread thin all over the world let alone the fact that there are countless specializations that each unit is capable of, but it still doesn't make sense to say that we wouldn't be able to allocate the resources if we needed them. Perhaps it's my misunderstanding and the Strategic Study-whatever group is just warning that we're not prepared at this very moment.It isn't militarily advantageous to flatten the civilian population. In an ideal battle you leave the civilian infrastructure intact and unharmed so that you aren't left with insurgent hell. The paper argues that your choices are to dresden the fuck out of your target or relive Blackhawk Down.
Okay, lemme 'splain. Let's say we're gonna take Lagos, Nigeria, shall we? After all, Boko Haram, Goodluck Jonathan, social inequality of Dickensian proportions and shit-tons of oil. Lagos is my huckleberry. It also has a population of 21 million (more than New York State) spread across a very New Orleans-like floodplain over an area roughly a quarter the size of Rhode Island - coincidentally, about 10% bigger than New Orleans. New Orleans proper? 400,000 people. Lagos proper? 18 million people. Let's assume one in a hundred of those people means you harm: there would therefore be half as many INSURGENTS in Lagos as there are PEOPLE in NoLA. And, for effect, they're hiding amongst double the population of NYC. Awright, but 66,000 active duty "personnel" in the SF. Figure roughly 1/4 of them are actual on-the-ground shock troops (more discussion here). That's okay, you're mostly going to use them to take out command and control targets so that the precision bombers can come through. And let's just pretend - for the sake of fun'n'games - that we can get 200,000 active duty marines into the harbor in one fell swoop and get them offloaded. I'm already in an environment owned by the enemy. person-for-person they're at parity. It's their city and I'm in the harbor. Meanwhile I've got major highways I can roadblock but we already know that's ineffective in a city the size of Fallujah. We're currently invading Manhattan with 200,000 ground troops. If I want tanks, I have to get them on the streets... and even a Bradley weighs more than a lot of bridges can take (fun fact: Soviet tanks and Soviet bridges were designed to be about 40% lighter than NATO armor for the explicit purpose of mobility - the Soviets could cross rivers, NATO couldn't). And I'm attempting to do all these things in such a way that the undecideds out there in that city of 21 million want to side with me, not their friends and neighbors that said the Imperialists were coming with bombs and tanks. Fast forward a few days. Yeah, I can start rolling C5s full of troops and IFVs into the airport but this city is surrounded by jungle and 170 million people. The North is essentially lawless. I've just become law'n'order for the whole place because the cops are either going to be useless or insurgents (been there, done that, got the war debt). And they're all chatting with each other via cell phone (or semaphore flag, or notes passed by kids) and for every "insurgent" I feel like taking out, I'm shooting up someone's playground. Remember: 250,000:1 bullet-to-kill ratio in Iraq (see previous link). How long before Muqtada al Sadr rises up to lead the city against the Infidel? If every "insurgent" convinces one of his buddies to join the cause, the "enemy combatants" outnumber my ground troops 2:1. And I don't even have to worry about my enemies: I have to worry about the shopkeeper that looks the other way when somebody plants an IED in the road because his daughter had her arm burned off by white phosphorus. I have to worry about the beat cop who says nothing about the SA-7 he saw going up the stairs because a stray bomb took out his mother's house (and his mother, and his three brothers). Fast forward a month. I've been attempting law an order in a city where I'm outnumbered 100:1 where I've also been shooting people regularly. And while there's now a carrier group parked in the bay and UCAVs circle incessantly, I've effectively militarized the population against me. I'm resupplying through the airport and the harbor; they're resupplying through the porous perimeter I can't hold worth a shit because it's a hundred miles long and I don't live here. I've concentrated my supply lines into two or three crucial choke points. My enemy has saturated the ground I claim to hold but I've effectively turned a functional city into a war zone. The locals are settling scores; Dad remembers Biafra. The water isn't potable so I've got newscasts of big-eyed children dying of cholera on Al Jazeera. I can wander anywhere I want unopposed so long as I'm in an up-armored Humvee because the heavy weaponry is concentrated around the airport and highways where we've now adopted a shoot-on-sight policy. Meanwhile, whatever conflict I intended to prevent has traipsed out to the parts of the country I don't control. Why was I here again? I'm no longer publicizing body counts because they're bordering on genocidal and I'm exercising a press blackout against all but my embedded reporters because holy fuck, we thought baghdad was bad... Take Mogadishu. Multiply by 20. Replace street-level drug crime with Islamic fundamentalism and you've got Lagos. And that, dear Pablo, is why we don't have the numbers. "You will kill ten of us. We will kill one of you. But in the end, you will tire of it first." - Ho Chi Minh
a) Thank you for your extensive and helpful response b) In the (certainly plausible) story line you're drawing here, I agree that the current circumstances of U.S. military strategy as well as military strength offer no chance at a positive result in, say, Lagos. Also holy shit, I didn't know there were that many people in Lagos. God damn. Yet, it's not Dresden, fine... now it's Operation Market Garden. Now it's Napoleon and Garibaldi marching on a target and creating, wait for it, the aforementioned full-scale war, nation against nation, the United States against the Nigerian people unified by perfectly justifiable anti-U.S. sentiments. So-- and don't get me wrong, I'm not trying to refute or disagree with what you're saying because I think we're coming to the same page-- by the end of your story we end up with an equal or greater military opposition and we now have no regard for civilian protection because we've made them all take arms against us. So just going off modern history here, we massacre and exterminate a population for defending itself and/or protecting its interests and we say something like- oh I don't know- "It was for the greater good." It seems to all come back around is all I'm saying. (To clarify again, I am veering away from the topic of numbers and going back to the point regarding dresden.) I don't think anything would, hypothetically, be stopping us from making the exact same mistakes and committing the exact same atrocities we have in all the wars of our past. Globalization and the U.N. will pressure us to ensure the protection of human rights/prosecute our war crimes? Come on, the Allies were tight back in WW2 too.
I think I didn't quite understand your question. Perhaps it comes down to this problem: Do you want to fight a war in Lagos? Or a war against Lagos? The premise of urban warfare is that you can conduct a military action within an urbanized area without reducing that urbanized area to a paintball arena. People lived in Sarajevo while Serbs and Croats were busily settling the score for 200 years of history, and continue to do so. A lot of it is still pretty shot up and it'll never be the same, but it's a long way from The Blitz. The argument of the paper is that above a certain point, "Sarajevo" is wishful thinking and "the Blitz" is the end result. Basically, you're going to quagmire above a certain population level regardless of your actions. It's interesting to me because architecture has far more of an impact on military strategy than a lot of people realize. Geoffrey Parker claims that the invention of the Star Fort effectively created the professional army and, therefore, the modern middle class. This is the US Military arguing, essentially, that above a certain size, cities cannot be held. That's almost a parallel conclusion to the military assessments of Star Forts: above a certain level of fortification, cities cannot be sieged. That's the true conclusion of the article: we no longer really know how to conduct the battles we can expect to fight. I don't know nearly enough to question whether this conclusion is correct, but it's a pretty stunning one to make. You're talking about a substantial percentage of the modern military-industrial complex being spent on tactics and armaments that will not, in fact, be useful.
This is the time for mechas to make their big debut. They could manuever in a city, step over cars and have sick robot fights. Sure, thousands would die from collateral damage, but that happens anyway. Would you rather die from the shockwave of an IED planted by insurgent forces, a tank shell that missed it's target, or a robot's rocket punch?
In my opinion there's only two possibilities, mecha, or cyber warfare. So either you get squished by a walking tank, or your entire infrastructure is shut down leading to mayhem. The future is looking bright boys and girls.
By the mid century it will be clear that wars are no longer fought between two armies but that they,ve become a media show where the object is to kill as many civilians as possible and then blame the "other" side. Armies become state sponsored terrorists who keep their populations hostage, with a silent agreement not to shoot other armed forces (because they might shoot back!). Refugees will be the responsability and social/economic burden for your enemy, so if they flee your way, turn them around or kill them. (actually what Julius Caesar did in Gaul.