ARMY WAR COLLEGE: Hours before Pyongyang conducted its latest nuclear test, military officers here at the Army War College began waging a wargame whose classified scenario is transparently concerned with North Korea. That is not happenstance.

[Click here for more coverage of the Army’s “Winter Wargame”]

After a decade of guerrilla warfare in Afghanistan and Iraq, the military is refocusing on the wider world, particularly the Pacific. The Army especially wants to get its arms wrapped back around nuclear, biological, and chemical threats. US troops trained to survive such attacks during the Cold War, and they sincerely expected to be “slimed” by Iraqi chemical weapons in 2003, but they have had little time to think about them since.

“We’ll probably have to scrape a little rust off,” one general acknowledged.

But it’s more than that. Both Cold War doctrine and current homeland security efforts focus on cleaning up after an attack. Now, the administration’s strategic guidance calls on the military to prevent one. After decades of a “reactive” approach, said one officer, “we require a true paradigm shift to become proactive.”

So there’s not only a lot to relearn about WMD: There’s a lot to unlearn as well. Said a senior civilian, bluntly: “We’re in kind of the same place with counter-WMD that we were in 2003 with counterinsurgency.”

That’s not exactly reassuring. But in contrast to COIN, at least, the Army is trying to figure out “CWMD” before the shooting actually starts.

No one involved, on or off the record, told Breaking Defense the specifics of the classified scenario. (Media were allowed to participate in unclassified portions of the “Unified Quest” wargame on the condition they did not identify participants by name). All they would say was the hypothetical crisis is set in 2020 and involves the collapse of a “failed state” with nuclear weapons — a description that’s frighteningly plausible for Pakistan.

But the fact that the fictional US forces were led by officers from US Army Pacific and 8th Army, headquartered in Seoul, made it pretty obvious which well-armed but politically rickety state they were discussing. Indeed, North Korea was almost certainly the subject of a classified cell in last year’s otherwise unclassified annual wargame as well.

For the Army, refocusing on the divided peninsula represents a return to the setting of both a formative disaster — the destruction of the ill-prepared Task Force Smith in 1950 — and the only enemy left on earth to threaten US interests with a large, conventional land force. (While China may count as an enemy, the threat it poses is mainly at sea and in cyberspace). And although the most of the Army put away its protective suits after Saddam’s WMD failed to materialize in 2003, the units in Korea could not.

It’s not that the military ever forgot about weapons of mass destruction. But it has always emphasized response, not prevention. In the Cold War, there was no way to preempt Soviet nuclear, biological, and chemical attacks, short of a US first strike. Since 9/11, the military’s limited counter-WMD capacity has been largely devoted to homeland defense, not to contigencies abroad.

The Defense Department overall musters “a 20,000-man CBRN [chemical, biological, radiological, and nuclear] response enterprise,” most of it from the Army, said one civilian working on homeland security. “We spent about a billion dollars on that last year.”

“How does that support PACOM [Pacific Command]?” asked another participant.

Said a third: “It doesn’t.”

“Homeland is the stated, clear lead priority,” interjected a general officer. But, he said, the Army also needs “a deployable capability” to counter WMD around the world.

“This is messy, expensive, and…if I represent the majority of the force, something we don’t want to deal with,” the general continued, bluntly, “but we have to deal with it, and it’s time to deal with it.”

“This has never been a high priority,” a civilian said a few minutes later, directly addressing the general. “In fact, I’ve watched you as the chair [at budget meetings] cut this priority.”

So the first part of the problem is limited resources: Even as budgets swelled post-9/11, the military had few dollars to spare for nuclear, biological, and chemical threats when troops were dying every day from homemade roadside bombs. Today, as the wars wind down, sequestration, the Continuing Resolution, and other budgetary dysfunction in Washington make for an ugly fiscal picture in the future, as well.

But a second part of the problem is institutional. “We don’t have a culture of ownership for this mission set,” said one senior officer. “Within DoD [the Department of Defense], we’re not sure who really owns this…. Nobody really wants it.”

Even within the Army, “we don’t have a single point of contact,” another officer agreed. Unlike other aspects of modern warfare, WMD does not have any institution in the Army charged as its official “proponent.”

“We’ve gotten the chem school more involved [the Army Chemical, Biological, Radiological, and Nuclear (CBRN) School at Fort Leonard Wood, Missouri],” the officer said, “but our shortfall is we don’t have a holistic approach for dealing with the components of CBRN.”

Instead, the necessary capabilities are located all over the place — and extremely varied. Convenient catch-all terms like “CBRN” or “WMD” obscure how different the threats and the necessary responses are.

“We may have made a mistake, fundamentally, in categorizing chemical, biological and nuclear in the same bucket,” said one civilian.

Chemical weapons are the oldest threat, dating back to World War I. Offensively, it takes tons of chemical warfare agents — like mustard gas, chlorine, or sarin — to poison even a portion of a battlefield, so much that they’re typically delivered by artillery barrage. Defensively, countermeasures such as gas masks, protective suits, and decontamination wash-downs have been refined for almost a century.

In contrast to chemicals, biological toxins — poisons derived from living organisms, like ricin — can be much deadlier per gram, albeit even more difficult to deliver in quantity. Infectious biological agents — i.e. germs, like anthrax — are even deadlier, although slower acting, because a tiny amount of virus or bacteria, once ingested, will eventually multiply within the body, an infection leading to illness or death. Contagious biological agents, able to spread from one victim to another like a plague, are the slowest but potentially deadliest of all: The 1918 flu epidemic, a natural outbreak, killed at least 20 million people around the globe, more than World War I.

But for sheer instantaneous destruction of an army or a city, nothing beats a nuclear bomb. That’s why the military is so concerned about countries like North Korea, Pakistan, and Iran.

Even a small nuclear explosion is more devastating than any conventional one. The radioactive contamination it leaves behind is far harder to keep out of the body than poison gas or germs, and it is far harder to clean up. Yet a nuclear warhead is compact and easy to hide. In fact — until it detonates — weapons-grade uranium is less likely to trigger a radiation detector than the potassium-40 in a shipment of bananas.

So detection, protection, and decontamination, not to mention the sheer number of casualties and refugees, are all more difficult for nuclear weapons than for other forms of WMD. If the Army has to focus on just one weapon of mass destruction — and limited resources will probably mean it must — then nukes are it.

The Army is hardly alone, of course. The other armed services have counter-WMD units of their own, most famously the Marine Corps’ CBIRF (Chemical-Biological Incident Response Force). The Energy Department has world-class scientists and the Nuclear Emergency Support Team (NEST). The FBI, CIA, and other intelligence agencies lead the hunt for terrorist networks.

By law, the military cannot even respond to nuclear emergencies at home until it’s called in by the Homeland Security Department, which in turn typically defers to state and local government. Overseas, it’s up to the State Department to call in the troops, usually on request of whatever foreign country has been hit, as happened in Japan after the Fukushima reactor meltdown.

The practical problem, though, said one wargame participant, is that “when it all goes to hell, the State Department is not equipped to respond.”

Neither is Homeland Security, Energy, or any other federal agency. Even within the military itself, only the Army — which provides much of the logistical and medical support to the other services anyway — has the sheer size to cope with a A-bomb-sized disaster. Even when it comes to prevention and preemption, while airstrikes and special operations forces can take out a specific nuclear facility, only the Army has the sheer manpower to isolate, secure, and search a many-mile-wide area where a warhead might be hidden.

“It’s not because other people aren’t doing their job,” one Army general told reporters. “It’s just we’re the largest force on the ground, we have the broadest set of capabilities in the Department [of Defense], and we’ve got the most depth.”

So the Army has to take a leading role against the weapons of mass destruction threat, the general said: “There isn’t anybody else to own it.”