Quảng Bình is the narrowest part of Vietnam, a strip of coastal plain squeezed between the Gulf of Tonkin and the Annamite Range, and everything in it was a target — the roads, the ferries, the rail line, the trail crossings into Laos, the passes at Mụ Giạ and Ban Karai that the American interdiction campaigns were built around. Putting a fixed installation into that landscape in 1969 was an act of some optimism. What made it survivable was the terrain itself: the tower karst of what is now Phong Nha–Kẻ Bàng National Park breaks sightlines and radar returns alike, and a strip laid along the valley floor between limestone towers is a difficult thing to find and a worse thing to bomb accurately. The Vietnam People's Air Force finished it in seven months and then let it be.

The aircraft that would eventually fly from Khe Gát were MiG-17Fs — subsonic, short-legged, and by 1972 comprehensively outclassed by anything the United States was putting into the air over North Vietnam. Used conventionally, they would have been shot down. Used once, from an airfield nobody had ever seen aircraft on, flown low over broken ground against ships whose crews had spent seven years without ever being attacked from the air, they were something else. The whole value of the place lay in its emptiness. Every month the strip went unused made the eventual sortie more likely to succeed, and the Vietnamese command was prepared to wait years for it.

The spring offensive of 1972 supplied the moment. On 19 April, two MiG-17Fs of the 923rd Fighter Regiment lifted off from Khe Gát, flown by Lê Xuân Dị and Nguyễn Văn Bảy — the second pilot of that well-known name, recorded as Bảy 'B'. Out over the Gulf of Tonkin, four American warships were working the gun line off Đồng Hới. Dị made two attack runs on the destroyer USS Higbee and missed both. On the third he put a 250-kilogram BETAB bomb squarely onto her aft five-inch gun mount, tearing it open, wrecking her steering and propulsion, and wounding four sailors on deck. By an accident of timing the turret was empty: a shell had jammed in the barrel minutes earlier and the gun crew had been sent forward. Nobody was killed. The second MiG attacked the cruiser USS Oklahoma City and missed.

This was the first air attack on American naval forces of the entire Vietnam War, and only the second occasion since 1945 on which US warships had been bombed from the air — the earlier case being the strike on USS Liberty, officially recorded as a mistake. The material result was one destroyed gun mount and four wounded men. The strategic result was that ships which had operated off the coast in near-routine safety now needed fighter cover, at exactly the moment the United States was trying to reduce its commitment. American accounts credit a Terrier missile from USS Sterett with downing one of the MiGs and count a second as probable. Vietnamese records say one aircraft came home damaged and both pilots came home alive. Those two versions have never been reconciled.

The retaliation arrived on 22 April, when thirty-three American aircraft struck Khe Gát. The airfield does not appear to have flown another operational mission; the records close it out in 1972, three years after it opened and three days after the one afternoon it mattered. Its afterlife is more ordinary than its history. The Hồ Chí Minh Highway, the modern trunk road that traces the wartime corridor down the western side of the country, now runs over the site, and the old runway lies buried beneath asphalt carrying tourist buses toward the caves at Phong Nha. Drivers pass over it without any reason to slow down. That is usually what happens to a place built to be invisible.