U.S. "Defense Responsibility"

1. Military Occupation and the Laws of War

Under the laws of war, particularly customary international law -- predating and later codified by instruments such as the Hague Conventions of 1907 and the Geneva Conventions of 1949 -- an occupying power assumes specific responsibilities in a newly conquered territory. These responsibilities include ensuring the security, order, and general welfare of the local population. The legal framework establishes that the occupier must act as a temporary steward, maintaining stability while respecting the rights of the inhabitants, and ensuring compliance with international norms.

Historical examples illustrate how these principles were implemented. During the Mexican-American War, U.S. forces established military governments in occupied regions, emphasizing public order and infrastructure. In the aftermath of the Spanish-American War, the U.S. occupation of the Philippines demonstrated both the challenges and obligations of military governance, including addressing insurgencies while maintaining civilian administration. Similarly, during World War II, U.S. occupations in Europe (e.g., Germany and Austria) and the Pacific (e.g. Japan and the Ryukyu Islands) were shaped by these legal and ethical duties. In these cases, the United States, as the legal occupier, bore responsibility for safeguarding life and property, administering justice, and preventing external threats.

These obligations highlight the dual role of the occupying power: to uphold humanitarian principles while protecting its own strategic interests. The interplay between these roles often defined the post-conflict trajectory of the occupied territories, influencing their governance, reconstruction, and eventual political status.

2. Common Defense Clause and Military Occupation

The "common defense" clause in Article I, sec. 8, cl. 1 of the U.S. Constitution grants Congress the power to provide for the nation's defense and security. This was originally implemented via the creation of the Dept. of War in 1789, which was reorganized as the Dept. of Defense in 1947. Traditionally, such defense and security matters have been interpreted as applying to the defense of U.S. states and formally recognized territories. However, historical precedents in territorial expansion suggest that the spirit of this clause extends beyond such formal boundaries to encompass any territory under U.S. military control.

When newly conquered territory comes under U.S. military occupation, the occupying forces are obligated to defend it against external threats. This responsibility aligns with the principle of common defense, as such areas, though not fully integrated into the United States, are nonetheless under its effective jurisdiction and military authority. For example, during the U.S. occupation of Japan after World War II, American forces actively protected the territory against potential threats, particularly during the early years of the Cold War, when fears of Soviet expansionism loomed large.

Similarly, in other occupied territories, such as the Philippines following the Spanish-American War, U.S. military authorities not only governed but also ensured defense against external and internal challenges. This obligation demonstrates that the common defense extends pragmatically to territories under U.S. control, regardless of their formal incorporation status. The U.S. has historically treated occupied territories as zones requiring protection, reflecting a constitutional and strategic imperative to secure areas under its de facto authority.

Such interpretations of the common defense clause reveal its adaptability in addressing geopolitical realities. By linking the clause to military occupation, it underscores the interplay between domestic constitutional principles and international responsibilities, highlighting the broader scope of U.S. obligations in the context of conquest and occupation.

3. Legal Precedent and Scholarly Interpretation

Legal scholars have extensively examined the obligations of the U.S. government in occupied territories, particularly focusing on the intersection of military governance and civilian protection. The general consensus is that the Constitution’s authority, especially its provisions related to military and foreign affairs, extends de facto to territories under U.S. military government jurisdiction. This extension of constitutional authority provides the framework for military governance and ensures that the occupying forces act within both domestic and international legal standards.

Judicial interpretations further reinforce these obligations. In cases such as Cross v. Harrison (1853), the U.S. Supreme Court addressed issues related to the governance of newly acquired or occupied territories, affirming that the military authority exercised there is ultimately subject to constitutional principles. Following the Spanish-American War, the U.S. administration of the Philippines reflected this dual framework: the occupying military acted as a governing authority while protecting civilian rights and adhering to international law.

These responsibilities were not merely operational but also strategic, as they helped stabilize territories in preparation for their eventual political resolution. The Philippines, for example, underwent a transition from military governance to a more civilian-led structure under American oversight. This evolution demonstrates how the U.S., as an occupying power, took on defense and governance obligations that were integral to its broader constitutional and strategic objectives.

Such legal precedents and scholarly interpretations highlight the continuity of the United States' role in occupied territories, emphasizing the extension of its constitutional powers to uphold order, provide protection, and ensure the welfare of the population.

4. Historical Examples and Defense Obligations

The United States’ historical military occupations provide concrete examples of its defense and governance obligations under the laws of war. During the Mexican-American War, U.S. forces established military control over occupied territories, ensuring security and maintaining public order. Similarly, after the Spanish-American War, the U.S. occupation of Cuba, Guam, Puerto Rico, and the Philippines underscored its dual responsibility to govern and defend. In Cuba and the Philippines in particular, military actions included suppressing insurgencies and preventing external interference, which reflected the practical application of defense obligations.

In the aftermath of World War II, U.S. occupations of Japan and Germany further demonstrate the scope of these responsibilities. American forces not only maintained security and order but also established extensive defense measures to protect these territories from potential third-party aggression, particularly in the context of rising Cold War tensions. While these actions were not explicitly tied to the "common defense" clause, they were underpinned by broader constitutional powers granted to Congress, such as the authority to fund and regulate the military. These powers, combined with international laws governing occupation, ensured that U.S. defense obligations were met.

The alignment of constitutional authority, military necessity, and international legal standards in these examples illustrate how the United States consistently assumed comprehensive responsibilities in occupied territories. These actions reveal a consistent pattern: territories under U.S. control were treated as zones requiring defense and governance, even before their final political status was resolved. This continuity affirms the principle that the United States, as a military occupier, holds defense obligations as an inherent part of its authority.

5. Scholarly Research on the "Common Defense"

Academic discussions on certain historical events have increasingly focused on the scope of U.S. military obligations in conquered or liberated territories, particularly as they intersect with constitutional principles and international law. One compelling area of inquiry is the application of the U.S. Constitution's common defense clause to such territories. In situations where the local government, including its military forces, has ceased operations, the responsibility for governance and defense shifts almost exclusively to the occupying power. In this context, it becomes difficult to dismiss the argument that the common defense clause must implicitly apply.

Scholars of international law and U.S. territorial expansion have engaged with these issues, often drawing on historical examples such as the Mexican-American War, the Spanish-American War, and World War II occupations. These cases provide a wealth of material for examining how the United States has historically approached its defense and governance obligations in newly occupied territories. Hopefully, legal scholars who analyze the extraterritorial application of U.S. power—whether through military governance, constitutional principles, or international legal frameworks—can offer additional insights into how these obligations have evolved over time in their future writings.

For deeper analysis, research could focus on works exploring the intersection of military occupation and constitutional law, such as studies on the Insular Cases or the legal status of post-war territories. Histories of U.S. military expansion, like those detailing the governance of Cuba or the Philippines, also provide critical context. These sources can help clarify how the common defense clause and related constitutional powers have been interpreted in practice, reinforcing the argument that defense responsibilities extend to U.S.-controlled territories and areas, even in the absence of formal annexation.

6. USMG Jurisdiction over Conquered/Liberated Territory

The default status of U.S.-conquered or liberated areas is that they fall under the jurisdiction of the U.S. Military Government (USMG). However, the extent and immediacy of military occupation by U.S. troops may vary based on several factors. For instance, delays in implementing direct military control could arise due to the large geographic scope of the territory, logistical challenges requiring detailed administrative planning, or the delegation of interim administrative authority to allied, coalition, subordinate, etc. third-party forces. These practical considerations, while affecting the administration of the occupation, do not alter the fundamental legal reality: the territory remains under U.S. jurisdiction through the USMG.

Regardless of the form or timetable under which military occupation is operationalized, the act of conquest or liberation establishes U.S. responsibility under international law. This responsibility persists until the final political status of the territory is resolved, ensuring that the United States retains obligations for governance, defense, and adherence to the laws of war during the interim period. Such continuity underscores the broader constitutional and legal framework within which the U.S. exercises authority in occupied or liberated areas, particularly as it relates to the common defense clause and military governance.

Additionally, the ethical implications of military governance cannot be overlooked. The U.S. bears not only legal but also moral responsibilities toward the welfare and rights of local populations in territories under its jurisdiction. Effective military governance requires engaging with civil society to enhance legitimacy and foster cooperation, ensuring that local voices are meaningfully included in decision-making processes. Such efforts can contribute to more effective and sustainable governance outcomes, mitigating resistance and laying the groundwork for eventual resolution of the territory’s political status.

Moreover, U.S. military officials must scrupulously adhere to the terms of post-war treaties and international legal standards in administering occupied territories. In cases where administrative authority has been delegated to allied, coalition, subordinate, etc. third-party forces, the U.S. retains a duty to ensure that no violations of international law occur under its jurisdiction. Prohibited actions include, but are not limited to, (announced) unilateral annexation of the territory, mass naturalization of the local population, implementation of military conscription policies, promulgation of a new constitution or legal code without proper authority, and seizure, expropriation, or confiscation of property, etc. Vigilance in upholding these principles is not only a legal requirement but also a moral imperative, reflecting the broader commitment of the United States to rule-of-law principles and human rights in occupied territories.

7. Conclusion

The analysis presented above strongly supports the conclusion that U.S.-conquered or liberated territories -- particularly those acquired during formally declared wars -- fall under an implied common defense responsibility. This conclusion is grounded in both constitutional principles and the customary laws of war. The U.S. Constitution’s common defense clause, while traditionally associated with domestic states and territories, logically extends to areas under military occupation. In such contexts, the occupying military assumes the dual role of protector and governor, a responsibility consistent with international legal standards.

From a practical perspective, the defense of such territories is essential for maintaining stability, ensuring security, and fulfilling the legal and moral obligations of a lawful occupier. Without effective defense, the occupying power risks undermining its control and leaving the local population vulnerable to external threats or internal disorder. Historical examples, ranging from the U.S. occupations of the Philippines and Japan to earlier cases like the Mexican-American War, demonstrate that defense obligations are an inherent aspect of military occupation.

In sum, while the common defense clause may not explicitly reference such situations, its underlying principles have been historically extended to U.S.-occupied territories. This reflects a broader constitutional and strategic imperative: to protect areas under U.S. control as part of the nation's military and geopolitical responsibilities. As such, the integration of these territories into the framework of U.S. defense obligations is not only reasonable but also a necessary component of lawful and effective military occupations.