DEMOCRACY WATCHNORTHCOM CONPLAN 3900: A Prelude to Insurrection Act Invocation?
The episodic call-up of National Guard units to respond to high-profile domestic events over the last 60+ years (enforcing civil rights laws, assisting with natural disaster recovery, etc.) is nothing new. What is new and decidedly ominous is the creation of specific, permanent military units designed and equipped to directly confront citizens engaged in unspecified, currently nonexistent “civil disturbances.”
On his first day in office for his second term as president, Donald Trump issued a slew of executive orders and proclamations. One proclamation declared a “national emergency” on the US-Mexico border. In that proclamation, Trump directed the Defense Department to “support the activities of the Secretary of Homeland Security in obtaining complete operational control of the southern border of the United States.” He also directed that within 90 days of the proclamation (April 20, 2025), the Defense and Homeland Security departments were to “submit a joint report to the President about the conditions at the southern border of the United States and any recommendations regarding additional actions that may be necessary to obtain complete operational control of the southern border, including whether to invoke the Insurrection Act of 1807.”
One week later, US Northern Command (NORTHCOM) began a planning process that culminated with representatives from other military commands and the Department of Homeland Security conducting a classified wargame on February 25–26, 2025, originally designated SECRET/NOFORN and named CONPLAN 3900 TITUS—Territorial Integrity of the United States.
A feature of the exercise was exploring various options for the potential use of military forces for domestic law enforcement, including the “Limited suspension of Posse Comitatus,” according to a partially declassified NORTHCOM slide deck obtained through a May 2025 Freedom of Information Act (FOIA) lawsuit brought by the Cato Institute. The records cited herein were not released until July 2026.
The Posse Comitatus Act, codified at 18 U.S.C.§ 1385, only permits the use of military forces to “execute the laws” domestically “in cases and under circumstances expressly authorized by the Constitution or Act of Congress.” One of the laws passed by Congress that could be used to bypass the Posse Comitatus Act’s restrictions is the Insurrection Act. Two slides provide clues that the Insurrection Act invocation issue was part of the wargame. The first slide, “Restated Mission and Intent,” revealed that NORTHCOM elements “BPT [be prepared to] assume the role of Lead Federal Agency for border control operations.”
A Trump decision to have NORTHCOM take over border security operations outside of DoD-controlled property (more on this below)—to include domestic law enforcement activities—would almost certainly require invoking the Insurrection Act, a fact that the wargame planners and participants clearly recognized, as the circled portion on the this slide reveals.
