Between August 2 and August 9, the Socialist Equality Party (US) held its biennial Summer School, attended by members of the SEP in the US along with delegates from all the sections and sympathizing groups of the International Committee of the Fourth International (ICFI).

The subject of the 2025 Summer School was Security and the Fourth International, the investigation initiated by the ICFI in May 1975 into the assassination of Leon Trotsky—co-leader of the Russian Revolution and founder of the Fourth International—who was murdered by Stalinist agent Ramón Mercader on August 20, 1940. As the investigation revealed, the Stalinist GPU prepared and organized the assassination through the systematic infiltration of agents into the Trotskyist movement, including the Socialist Workers Party in the United States.

Today, the World Socialist Web Site publishes the introductory report to the school, “The Place of Security and the Fourth International in the history of the Trotskyist movement,” delivered by David North, chairman of the SEP (US) and the International Editorial Board of the World Socialist Web Site. In the coming weeks, the WSWS will post the video and text of all the lectures presented at the school.

Over seven days, the summer school reviewed in detail the Security and the Fourth International investigation, situating it within the historical trajectory of the Trotskyist movement. This was accomplished through 29 intensive lectures, a significant number of which were delivered by newer members of the movement. As North noted in his opening remarks, “We have before us a very challenging week. The lectures will encompass a huge amount of material relating to history, politics and even law. But we are living in challenging and dangerous times, and objective events will impose huge demands upon our cadre.”

The school began with lectures on Trotsky’s Theory of Permanent Revolution, the strategic foundations of the 1917 October Revolution and the program of world socialist revolution. These lectures established the continuity connecting the perspective that led the October Revolution to victory, Lenin’s “last struggle” against nationalism and bureaucracy in the Soviet state, and the Left Opposition’s fight against Stalinism and the theory of “socialism in one country.” From there, the lectures traced the vast and horrific consequences of the Stalinist repudiation of international socialism. The betrayal of the 1926 General Strike in Britain and the Chinese Revolution of 1925–27, the catastrophic defeat of the German working class in 1933, and the betrayals in Spain and France in the 1930s paved the way for the triumph of fascism in Europe and the outbreak of the Second World War.

Of exceptional significance was a lecture which documented the immense influence within the Soviet Union of the Trotskyist opposition to the Stalinist bureaucracy well into the 1930s.

The school then examined the Stalinist campaign of political genocide against the revolutionary Marxist vanguard. The Moscow Trials and the Great Terror of 1937–38 were the centerpiece of a vast purge aimed at eradicating every surviving representative of the October Revolution. Between 1935 and 1940, nearly 2 million people were arrested on political charges in the Soviet Union, of whom 688,503 were shot. Thousands of socialist workers and the intelligentsia were annihilated: astronomers, biologists, physicians, historians, philosophers, musicians, writers and poets. 

Leon Trotsky, co-leader of the October Revolution and founder of the Fourth International, was the central target of this campaign of terror. After a decade of relentless persecution and the murder of many of his closest collaborators—including his son Lev Sedov—Trotsky was assassinated in Mexico on August 20, 1940 by GPU agent Ramón Mercader.

The second half of the school provided a detailed account of the Security and the Fourth International investigation. “With the initiation of the Security and the Fourth International investigation,” David North explained in his introduction, “the Trotskyist movement passed onto the offensive against the counter-revolutionary bureaucracies.” Launched in the face of slanders, provocations and lies from the apologists of Stalinism, the investigation established—on the basis of meticulously documented facts—the truth of the allegations it advanced. 

The lectures reviewed the investigation’s exposure of the operations of a network of GPU agents operating within and around the Fourth International prior to the assassination of Trotsky, including the assassin Mercader; Mark Zborowski, the most important GPU agent who was responsible for the murder of several leading Trotskyists, including Erwin Wolf, Ignace Reiss, Sedov and Rudolf Klement; Sylvia Callen, the secretary of SWP leader James Cannon; and Joseph Hansen, one of Trotsky’s secretaries at the time of the assassination, who later became an informer for the FBI.

They addressed critical turning points in Security and the Fourth International: the background to its initiation in 1975; the publication of key documents revealing the operations of GPU agents in the conspiracy to assassinate Trotsky; the uncovering of evidence of SWP leader Joseph Hansen’s meetings with both the GPU and the FBI; and the 1977 assassination of Workers League member Tom Henehan.

Three lectures detailed the origins and development of the Gelfand Case, initiated in 1979 by Alan Gelfand, who was expelled from the SWP for asking questions about Hansen’s ties to the GPU and FBI and the party’s cover-up of the role of Sylvia Callen as an agent of the GPU. In the face of united opposition from the SWP leadership and the state, Gelfand sought to compel the government to reveal and remove its agents from the party. The depositions conducted during the case provided irrefutable evidence that the SWP leadership was compromised by government agents, and the trial concluded with the release of grand jury testimony confirming that Callen was an agent of the GPU.

The Security and the Fourth International investigation exposed not only the operations of the Stalinist and imperialist state but also the political forces that sought to block and discredit it. As North explained in his introductory report:

The concern with historical experience, political principles and the programmatic foundations of the Fourth International that formed the basis of the education of the cadre of the International Committee was the polar opposite of the crude pragmatism, opportunism and atmosphere of cynicism that prevailed within the Socialist Workers Party and the Pabloite United Secretariat. … The leaders of these organizations could not be swayed by the evidence uncovered by the International Committee, no matter how damning.

Fifty years after its initiation, the Security and the Fourth International investigation has stood the test of time. Its conclusions have been confirmed and strengthened by new evidence, including material released after the dissolution of the Soviet Union. These documents exposed critical details of the assassination plot, such as the role of Robert Sheldon Harte—an SWP member sent to Mexico to serve as a guard—who was in fact a Stalinist agent. In the past five years, additional evidence, reviewed at the school, has shed new light on the role of Sylvia Ageloff, whose personal relationship with Ramón Mercader was used to facilitate Trotsky’s murder.

The fight for security has direct and urgent relevance to the present political situation. The SEP’s 2025 Summer School concluded just days before Trump deployed the military onto the streets of Washington D.C., a critical stage in the ongoing conspiracy to establish a fascistic dictatorship in the United States. This assault on democratic rights is part of a global trend, unfolding alongside the ongoing genocide in Gaza, the US-NATO war against Russia, and the intensifying preparations for war against China. In every country, the ruling oligarchy is pursuing a program of social counterrevolution, aimed at destroying the living standards and rights of the working class.

At the same time, mass opposition is developing in the working class and among young people, driven by the deepening crisis of capitalism. The decisive question, however, is that of leadership. The building of such a leadership is inseparably bound up with bringing forward the history of the socialist movement, including the strategic lessons of the Security and the Fourth International investigation. The body of evidence reviewed at the school will form the basis for lectures and meetings in the coming months to mark the 85th anniversary of Trotsky’s assassination and to deepen the political lessons of the struggle waged to uncover the truth.

All readers of the World Socialist Web Site are urged to study carefully the lectures from the SEP 2025 Summer School which will be published in the coming weeks, as an essential preparation for the political struggles now unfolding in the United States and throughout the world.