Walled Off.

• Author: Howell, Llewellyn D., Jr.
• Position: WORLD WATCHER

MORE than a century ago, poet Robert Frost captured the dilemma now faced by U.S. foreign policy decisionmakers regarding walls. A border wall dividing two countries or a wall separating two farms, conceptually, are not unlike each other. In "Mending Wall," Pres. Donald Tramp takes on the role of the farmer who insists that "good fences make good neighbors." Modern Democrats and others are of the poem's view that "something there is that doesn't love a wall."

Walls generally have not worked. We see the contrasts throughout human history. The Great Wall of China did not stop the Mongols from the north, nor did the circling walls of Hyderabad prevent invasion. Roman walls did not stop the Huns, and the Maginot Line did not stop Germany. There are other examples of walls and their failures.

The walls and fences already in place along the U.S. southern border easily have been circumvented --go through a fence; cut it; go over or under it. Tunnels appear and reappear under walls almost as quickly as they are discovered --and then re-created in another spot. Israel has built walls around Jerusalem that extend 20 feet below ground to obstruct tunneling--and still, Gaza patrols have to be added along the surface. Most of the illegal immigrants in the U.S. arrive with legal visas and just pay for airfare to, in a sense, fly over the fence.

Building a wall along the southern border of the U.S. encounters the same forces that Frost faced in his New England stone wall dividing farm properties. When frozen ground swells and hunters pull at Frost's wall, at the U.S./Mexico border, airplanes and ships circumvent fences, and border crossers fan out across the desert, affirming the uselessness of a physical structure. More illegal immigrants are in the U.S. because they overstayed their visas rather than by coming overland from Mexico into Texas or California.

The effort to build walls to stop illegal immigration is reminiscent of the old saw about the man crawling about underneath a streetlight at night. When a passerby wonders what he is doing, the man explains that he is looking for his glasses. When asked where he lost them, the man points down the dark street: "Over there." "Then why are you looking here?" "The light is...