10 U.S. Military Plans That Were Top Secret Until Recently

Throughout history, governments and military organizations have devised secret plans to secure their nation’s interests or gain an advantage over adversaries. Many of these plans remained classified for decades, only coming to light through declassified documents or whistleblowers. These revelations often provide a fascinating glimpse into strategies, fears, and ambitions that shaped global events, offering insight into the lengths nations would go to achieve their objectives.

From Cold War espionage to ingenious wartime deception, these once-hidden plans reflect the complexities of geopolitics and the unpredictable nature of international conflict. Here are 10 military plans that were top secret until they were recently revealed.

Related: 10 Bizarre Failed Military Experiments and Projects

10 Operation Northwoods

In 1962, at the height of Cold War tensions, the U.S. Department of Defense devised Operation Northwoods, a shocking plan to justify military intervention in Cuba. Crafted by the Joint Chiefs of Staff, the plan called for the CIA to stage false-flag attacks on American soil and blame them on Fidel Castro’s regime. Proposed actions included bombing U.S. cities, sinking refugee boats fleeing Cuba, hijacking planes, and even orchestrating mock funerals for victims of fake attacks. The goal was to manufacture public outrage, creating the political momentum needed to support an invasion of Cuba.

One particularly audacious element involved faking the downing of a civilian airliner. The plan suggested replacing a commercial aircraft with a drone, simulating its destruction over Cuban waters to make it appear as though Castro’s forces were responsible. Though never implemented, the plan underscores the extreme lengths U.S. leaders were willing to go during the Cold War. Declassified in the 1990s as part of the Kennedy assassination documents, Operation Northwoods horrified the public. It became a cautionary tale about the dark side of military strategy.^[1]

9 Operation Paul Bunyan

Operation Paul Bunyan, executed in August 1976, was the U.S. military’s response to a violent incident in the Korean Demilitarized Zone (DMZ). Two U.S. Army officers, Captain Arthur Bonifas and Lieutenant Mark Barrett, were brutally killed by North Korean soldiers while attempting to trim a poplar tree that obstructed the view of an observation post. The murders shocked the American military, prompting an extraordinary show of force disguised as a simple tree-removal mission.

The operation involved a massive task force that included over 800 soldiers armed with automatic weapons and backed by tanks, helicopters, B-52 bombers, and F-4 Phantom jets. Engineers arrived with chainsaws and military-grade equipment to remove the tree. To emphasize the seriousness of the mission, the U.S. ensured that North Korean troops, who were observing from nearby positions, could see the overwhelming firepower assembled against them. While the operation succeeded without further violence, its declassified details revealed the intensity of Cold War brinkmanship in the Korean Peninsula.^[2]

8 Project Iceworm

Project Iceworm was a bold Cold War initiative by the United States to hide nuclear missiles under the Greenland ice sheet. The project aimed to create a vast network of tunnels spanning thousands of miles, where missiles could be moved undetected and launched in the event of a Soviet attack. The U.S. established Camp Century, a prototype base built entirely under the ice, to test the feasibility of the concept. Equipped with living quarters, laboratories, and even a nuclear reactor for power, the camp was an engineering marvel.

However, scientists soon discovered a critical flaw in the plan. The ice sheet was far more dynamic than anticipated, with constant movement and shifting that made maintaining the tunnels impossible. The project was quietly abandoned, but its declassification in the 1990s caused controversy in Denmark, as the Danish government had not been informed about the nuclear components of the operation. Today, remnants of Camp Century remain frozen in time, slowly being revealed as the ice melts due to climate change.^[3]

7 Operation Gladio

Operation Gladio, a clandestine NATO program during the Cold War, aimed to establish “stay-behind” armies in Western Europe. These secret units were trained to resist Soviet invasion by engaging in sabotage, guerrilla warfare, and intelligence gathering. Funded by the CIA and British MI6, Gladio was implemented in numerous countries, including Italy, Belgium, and Germany. While its original purpose was defensive, declassified documents revealed that some units became embroiled in domestic politics, carrying out false-flag attacks to discredit left-wing movements.

One of the most infamous incidents linked to Gladio was the 1980 Bologna train station bombing in Italy, which killed 85 people and injured over 200. Investigations suggested that far-right groups, potentially supported by Gladio operatives, were responsible for the attack, fueling distrust in NATO’s covert activities. The program’s exposure in the 1990s shocked Europe, highlighting the murky intersection of anti-communist paranoia and domestic terrorism during the Cold War.^[4]

6 Project Eldest Son

During the Vietnam War, the CIA launched Project Eldest Son, a covert operation designed to undermine the morale of North Vietnamese soldiers by sabotaging their ammunition. CIA operatives secretly replaced gunpowder in captured ammunition with high explosives, causing weapons to explode when fired. These tampered munitions were then discreetly reintroduced into enemy supply lines, making it appear as though North Vietnam’s own supplies were faulty.

The psychological impact of the operation was significant. North Vietnamese troops began to distrust their weapons, and rumors spread that Chinese-manufactured ammunition was defective. Though the physical damage caused by Project Eldest Son was relatively minor, its ability to sow fear and uncertainty made it a potent form of psychological warfare. The operation was declassified years later, revealing the creative, if ethically questionable, strategies employed during the Vietnam War.^[5]

5 Operation Washtub

Operation Washtub, developed by the CIA in the 1950s, was a Cold War contingency plan aimed at defending Alaska in the event of a Soviet invasion. The plan sought to create a secret network of civilian operatives acting as guerrilla fighters and intelligence gatherers. Fishermen, bush pilots, and trappers were recruited due to their deep familiarity with Alaska’s harsh and remote terrain. This would be critical in a scenario where formal military control was lost.

Participants were trained in sabotage, espionage, and survival techniques. They were also provided with caches of weapons, explosives, and radios, which were hidden throughout the wilderness. The operation remained secret for decades, with its declassification in 2014 revealing the extraordinary lengths the U.S. military was willing to go to protect Alaska’s strategic location. While the invasion never occurred, the existence of such a plan underscored the paranoia and high stakes of Cold War geopolitics.^[6]

4 The Manhattan Project’s Hidden Cities

The Manhattan Project, the top-secret U.S. initiative to develop nuclear weapons during World War II, is well known. However, the hidden cities it created are less commonly discussed, like Oak Ridge, Tennessee, and Los Alamos, New Mexico. These towns were built entirely from scratch to house workers and facilities needed for the project. Shielded from public knowledge, these cities had their own infrastructure, schools, and even stores, but their residents were often unaware of the project’s true purpose.

At its peak, Oak Ridge employed over 75,000 people, most of whom were engaged in uranium enrichment. Security was tight, with workers monitored to prevent information leaks. Residents often joked about their “mystery town” but accepted the secrecy due to the war effort. The full details of these cities, including their role in producing the bombs dropped on Hiroshima and Nagasaki, remained classified until after the war. Their stories reflect the immense scale and secrecy of the Manhattan Project.^[7]

3 Operation Paperclip

Operation Paperclip was a controversial post-World War II U.S. program to recruit German scientists, including many with Nazi affiliations, to work on American military and space projects. The U.S. aimed to secure technological expertise while denying it to the Soviet Union. Among the 1,600 scientists brought to the U.S. were figures like Wernher von Braun, who became instrumental in developing NASA’s Saturn V rocket.

Many of these scientists had direct ties to Nazi war crimes, including work on weapons programs that used forced labor. To avoid public backlash, the U.S. government sanitized their records, omitting damning evidence of their involvement in the Third Reich. Declassified documents revealed the full extent of the operation, sparking debates about the moral compromises made during the early Cold War. Despite its controversy, Operation Paperclip profoundly impacted American scientific advancement.^[8]

2 Operation Mincemeat

Operation Mincemeat, executed by British intelligence during World War II, was one of the most audacious deception plans in military history. The operation involved planting false invasion plans on the body of a deceased man, dressing him as a British officer, and releasing the body near the Spanish coast. The documents suggested that the Allies were planning to invade Greece rather than their actual target, Sicily.

The body, identified as “Major William Martin,” carried fake letters, personal effects, and official-looking documents. Spanish authorities passed the information to German intelligence, who redirected their defenses accordingly. The success of Operation Mincemeat was critical in ensuring the success of the Allied invasion of Sicily in 1943. Declassified decades later, the story of the operation has become a celebrated example of wartime espionage ingenuity.^[9]

1 Operation Able Archer

Operation Able Archer was a 1983 NATO military exercise designed to simulate a nuclear war scenario. Unbeknownst to its planners, the exercise was so realistic that it alarmed the Soviet Union, which believed it could be a cover for an actual nuclear first strike. As a result, Soviet forces went on high alert, preparing for a potential counterattack.

The exercise involved encrypted communications, high-level decision-making drills, and even simulated nuclear launches. Declassified documents revealed that the Soviet Union interpreted the heightened activity as genuine war preparations, bringing the world dangerously close to nuclear conflict. Historians have since argued that Operation Able Archer represents one of the most precarious moments of the Cold War, illustrating how miscommunication and mistrust could have had catastrophic consequences.^[10]