“The North Koreans are not a reasonable people,” Ms. Lee said at the beginning of our trip. It was less a warning than a statement of fact.

The bus tour of the Korean Demilitarized Zone—the four-kilometer-wide ribbon of land that bisects the Korean Peninsula—left from downtown Seoul at eight in the morning but had begun raining long before. The travel agency was clear about the dress code: “No faded or torn jeans, sandals, leather pants, shorts, sleeveless shirts, sweatpants, slippers, or military-style clothing.”

I assumed the dress code was for our safety but Ms. Lee, our friendly tour guide, explained that if we wore ragged clothes, pictures of us could be taken and used as propaganda: proof that people in the South couldn’t afford nice clothes. I didn’t know what to make of this sudden concern for national image. Surely the North Korean propaganda machine could just as easily download pictures of poorly-dressed South Koreans.

As our bus cruised along Freedom Highway, Ms. Lee gave us some statistics about the North. Soldiers spent 10 years stationed at the border. If they performed well they could earn a trip home. When Kim Il-sung was in power, everyone had jobs and universal health care—things weren’t bad at all.

She patiently catalogued the horrors of the ongoing separation: families torn apart, the occasional bursts of violence across the border, the widespread starvation and destitution in the North. Then she did something strange: she asked our group of bleary-eyed tourists if we had any ideas about how to resolve the situation. I thought it was a rhetorical flourish but she repeated her question and added, “If you have any ideas, please let us know.” It was unclear whom she meant by “us”—the tourism agency? The South Korean people? It seemed unlikely that any novel ideas would arise from our humble bus, and even less likely that any sensible suggestions would be passed up the chain of command to the relevant ministries. I couldn’t help but wonder if tour guides in Gaza posed a similar question to their travelers.

When we reached the DMZ, we boarded a military bus and were acquainted with a new set of rules: no chewing gum, drinking water, or standing up in the bus. Cameras were allowed but we could only take pictures at specified locations. We signed a waiver that basically said, whatever happens, happens. And we had to abandon our umbrellas, leaving us defenseless against the rain.

We drove to a parking lot and walked through a concrete building, called the Freedom House, to the Joint Security Area. It was just like all the photographs. Three longhouses painted robin egg blue. A concrete slab between the buildings indicating the Military Demarcation Line. Three South Korean guards, facing the north, fists clenched, frozen in perpetual war.

As the MP on duty led small groups of us into the MAC Conference Room for pictures, a group of tourists appeared in front of Panmungak, the North Korean building that stood across from the Freedom House. As they waved to us, I remembered what Ms. Lee had told us on the bus: “When you get to the border, do not touch anything. Do not stare. If people wave at you, do not wave back. And most of all, do not point.” When s0meone asked why we couldn’t wave, Ms. Lee kindly reminded us, “The North Koreans are not a reasonable people.”

I noticed that the group on the North Korean side carried umbrellas and took pictures liberally. Some of them wore shorts, though even they heeded the no leather pants rule. “They are Chinese tourists,” the soldier accompanying us said. The Chinese tourists waved enthusiastically but we kept our hands at our sides. I imagined a picture of our stoic tour group on a North Korean propaganda poster: people in South Korea are antisocial.

Drenched in rain and watching the waving crowd just north of us, separated by six soldiers and a gulf of understanding, it was hard to see the Korean situation as anything more than a wound that man had inflicted upon himself—the bitter fruit of a few men squabbling for power, of twisted ideology and hollow nationalism. In any other place we might have called out to them, waved and smiled to affirm our common humanity. But across this imaginary line that man had drawn over the unwitting earth, they seemed a world away.

An American in our group asked why the Chinese tourists were allowed to wave and take pictures.

“They are in violation of the rules but the North Koreans know we won’t shoot,” our soldier answered.

“What will they do if we take pictures?” asked the American.

Our soldier thought about this for a moment. Then he simply said, “I don’t know.”