On Jan. 21, 1968, North Vietnamese troops attacked the U.S. Marine garrison at Khe Sanh in South Vietnam near the border with Laos. A 77-day siege ensued, with the U.S. pouring in ever more firepower. The U.S. would drop 100,000 tons of bombs because Gen. William Westmoreland was determined that Khe Sanh not become another defeat like Dien Bien Phu, which had effectively ended France’s colonial presence in Vietnam 14 years earlier.

And it didn’t. Eventually the siege was relieved and the attacking forces melted away, having suffered more than 5,000 fatalities (while the defenders lost about 350 men).

Today, no one except some veterans and military historians remembers Khe Sanh because in the end it had scant strategic significance: Even though the U.S. won the battle, it lost the war. Not long after having “liberated” Khe Sanh, the U.S. dismantled the base because it served little purpose.

This history is worth mentioning because of the parallels, limited and inexact to be sure, between Khe Sanh and Kobani, a Kurdish town in northern Syria. Jihadist forces of Islamic State, also known as ISIS, have been besieging Kobani for weeks, and the U.S. has been ramping up efforts to prevent the town from falling. U.S. airstrikes have apparently taken a heavy toll, eliminating ISIS fighters, artillery, armored vehicles and other heavy weapons. Airstrikes have now been joined by airdrops of weapons and ammunition to the Kurdish defenders. Turkey, which had hitherto not lifted a finger to save Kobani, announced Monday that it would allow Iraqi Kurdish fighters to traverse Turkish territory to join in defending the town.

Kobani no longer looks to be in imminent danger of falling. It is even possible that ISIS will give up the fight and pull out. If this happens, it will certainly be good news. The remaining residents of Kobani would be saved from slaughter and their relief would give a moral boost to anti-ISIS efforts. But any celebration should be muted. Winning at Kobani will be no more devastating to ISIS than was the American victory at Khe Sanh to North Vietnam.

The problem is that ISIS can readily replace the fighters it loses in Kobani, and heavy weapons are not essential to its guerrilla style of warfare. Even as ISIS is losing a little ground at Kobani, it is gaining strength elsewhere....