Key point: North Korean aggression and horrible treatment of American POWs could have led to a massive retaliation.

A U.S. Army light freighter launched during World War II, the fifty-four-meter-long Pueblo had been recommissioned by the Navy in 1966s to serve as an “environmental research ship,” with two civilian oceanographers on board. This was a flimsy cover for the truth: the Pueblo was a spy ship, charged with intercepting and recording wireless transmissions and monitoring electronic emissions. Periodically, the Pueblo would transmit its findings using a sixteen-foot parabolic antenna on its deck to beam a signal towards the moon, where it would reflect back to the Earth for reception by Navy antennas in Hawaii and Maryland.

The lightly armed and ponderous Pueblo—capable of a maximum speed of only thirteen knots (fifteen miles per hour)—was not supposed to place itself in real danger, however. Like other “technical research ships,” it could sail safely within international waters—no closer than twelve nautical miles from shore—and still listen in. The Soviet Union had its own spy ships, and so both sides of the Cold War had to tolerate the presence of the others’ electronic spies.

Today, signals intelligence remains a common form of espionage—and a basically legal one, so long as the ships involved do not stray into territorial waters and aircraft stick to international airspace. Recently, the Russian spy ship Viktor Leonov was observed thirty miles off the U.S. East Coast. U.S. Air Force RC-135 Rivet Joint aircraft routinely intercept signal traffic from North Korea and other nations. However, these electronic spies can only operate so long as the nations they are spying on respect the norms of international law—a risky proposition when tensions are high and the nation in question is governed by a capricious regime.

That January, the Pueblo was assigned by the NSA to intercept signal traffic from Soviet ships in the Tsushima Strait between Japan and Korea, and gather intel on North Korean coastal radars and radio stations. Her mission proceeded uneventfully until it encountered a North Korean subchaser (a corvette-sized vessel) on January 20. Two days later, it was spotted by two North Korean fishing trawlers, which passed within thirty meters of it. The Pueblo’s captain, Lt. Cmdr. Lloyd Bucher, informed the U.S. Navy and proceeded with the final phase of his mission.

Bucher was left unaware, however, that tensions between the two Koreas had just escalated dramatically. Near midnight on January 21, thirty-one disguised North Korean infiltrators came within one hundred meters of the South Korean presidential residence, the Blue House, in an attempt to assassinate President Park Chung-hee before being confronted and dispersed in a blaze of gunfire and exploding hand grenades. A shaken President Park put his troops on high alert and pressed for the United States to retaliate.

At noon on January 23, the Pueblo once again encountered another SO-1–class subchaser. The cannon-armed vessel closed on the Pueblo at high speed and challenged its nationality, to which Bucher raised the American flag. Next, the smaller boat transmitted: HEAVE TO OR I WILL FIRE. Bucher replied I AM IN INTERNATIONAL WATERS. In fact, the U.S. Navy stipulated that he keep his vessel several miles outside the boundary.

The subchaser’s captain was not satisfied, and continued to close on the Pueblo. Soon afterwards, two North Korean MiG-21 fighters swooped low over the 890-ton spy ship, and three P-4 torpedo boats joined the subchaser to surround the American vessel. Bucher turned the ponderous Pueblo around and made full speed eastward, managing to worm his ship away from a torpedo boat that attempted to land a boarding party toting AK-47s. The North Korean boats began raking the Pueblo with heavy machine-gun fire and blasting at it with the fifty-seven-millimeter cannon on the subchaser. Shrapnel sprayed across the bridge, wounding Bucher.

The Pueblo’s only weapons were two unloaded .50 caliber machine guns wrapped up in ice-coated tarps. (The spy ships were supposed to keep their defensive weaponry discrete.) The machine guns lacked gun shields and only one crewmember had been trained in their use. Bucher judged that any crew members attempting to load and fire the weapons would be massacred by the nearby boats, and that a few .50 caliber machine guns would not be of much use against an adversary armed with torpedoes and cannons.

Bucher was in radio contact with the U.S. Navy, but it had no forces ready to come to his ship’s aid. The four F-4 Phantom fighters on alert on the carrier USS Enterprise, roughly six hundred miles away, were not loaded with antiship weapons and would take an hour to rearm. Eventually, the U.S. Air Force scrambled a dozen F-105 fighter bombers from Okinawa. “Some birds winging your way” was the last message Bucher received. The aircraft never arrived, however; it turned around while over South Korea.

Meanwhile, a second subchaser and a fourth torpedo boat had joined the assault on the Pueblo. Reluctantly, Bucher ordered his crew to begin destroying the classified documents and encryption gear on his ship, and signaled the North Korean ships that he would comply with their instructions. He turned the Pueblo back towards North Korean waters, but proceeded at only four knots to buy his crew—and the promised air support—more time.

But progress was slow. The crew had only two paper shredders and a single incinerator purchased by Bucher before the mission, using money from the crew’s recreational fund after the U.S. Navy refused his request for a rapid-destruction device. The crew tried its best anyway, tossing top-secret documents into the water, bashing sophisticated encryption machines with fire axes and sledgehammers, and attempting to create a bonfire out of yet more classified material.

There were simply too many documents. Bucher halted the Pueblo just before entering North Korean waters in an attempt to delay. The North Korean vessels promptly opened fire again, and a fifty-seven-millimeter shell nearly tore the leg off of fireman Duane Hodges, causing him to bleed to death. Ultimately, Bucher turned the ship back on course. At 3 p.m., North Korean sailors finally boarded the ship, blindfolding and beating the crew and piloting the Pueblo into Wonsan harbor. The crew was then paraded through a mob of enraged civilians into captivity.

The North Korean attack came at the worst possible moment. Seoul feared renewed attacks across the demilitarized zone, and threatened to withdraw South Korean troops from Vietnam. The war in Vietnam was heating up, as a North Vietnamese forces embarked on a series of preliminary attacks culminating in the epic Tet Offensive. A CIA A-12 spy plane from Project Blackshield located the Pueblo in Wonsan harbor on January 28. CIA director Richard Helms thought the North Koreans had launched the attack as part of a Soviet plot to relieve pressure on Vietnam.

Declassified documents reveal that President Johnson considered options ranging from mining Wonsan harbor or organizing a naval blockade, to launching a battalion-sized ground attack on part of the demilitarized zone and air strikes. Ultimately, however, he chose to go with a show force, deploying hundreds of combat aircraft and three aircraft carriers to South Korea, and mobilizing fourteen thousand Air Force and Navy reservists. Soon the Soviet Union offered to aid in securing the release of the Pueblo’s crew if the United States drew its forces back down. Not wanting to get drawn into a second Korean War just as fighting was intensifying throughout South Vietnam, Johnson decided to draw down his forces, and offered Seoul additional military aid on the condition that it did not instigate a clash with North Korea.

Pyongyang, for its part, trumpeted its capture of the Pueblo, which it falsely claimed had intruded in North Korean waters. (North Korea defines “international waters” as beginning fifty nautical miles, rather than twelve, from its shores.) In time, North Korea began issuing photos of the captured American crew and a signed confession from Captain Bucher, causing the CIA to assemble a psychological profile of the Pueblo’s commander in an attempt to gauge his loyalty. The crew’s plight evoked an outpouring of sympathy in the United States, and even inspired a Star Trek episode.

In truth, the Pueblo’s crew was being brutally tormented, subject to daily beatings and undergoing hours of interrogation. Captain Bucher in particular was battered until he urinated blood, made to sit through his own mock execution, and shown a mutilated alleged South Korean spy as a warning of the consequences of not cooperating. At one point he went on a five-day hunger strike to protest the wretched food provided to his crew, which was so inadequate that one petty officer lost 40 percent of his bodyweight and nearly went blind. Finally, a North Korean interrogator threatened to execute the Pueblo’s youngest crewmember, nineteen-year-old Howard Bland, in front of Bucher if he did not sign a confession, to be followed by the rest of his crew. This threat finally moved Bucher to sign the confession.

The American crew was eventually moved to a better facility, where they were inundated with propaganda videos. The sailors attempted to clandestinely resist by formulating oddly worded confessions and flipping their middle fingers when posing for photos, which they explained was a “Hawaiian Good Luck” sign to their interrogators. Unfortunately, a Time magazine article eventually gave this ploy away to their captors, who subjected the prisoners to a week of brutal torture as a punishment.