Military Intervention: A Checklist of Key Considerations


From Parameters, Winter 1995, pp. 53-58.

Circumstances under which the United States should intervene militarily on behalf of threatened US interests overseas became the subject of intense debate in 1984, when Secretary of Defense Weinberger prescribed six preconditions that received mixed reviews.[1] Disputes within and between the executive and legislative branches have intensified since post-Cold War complexities replaced the US-Soviet confrontation.[2] Criteria for employing US armed forces as foreign policy instruments are still in flux.[3] It is possible to identify considerations that might help US leaders determine whether military power is appropriate in any given instance, including cases that are benign to begin with. Insights in seven categories familiar to strategists--national interests, threats, political-military objectives, policy guidance, planning options, resources, and public opinion--could help underpin decisions to intervene or abstain and to ascertain whether ongoing military operations seem warranted. Policymakers must determine which interests are worth a fight, relationships between political objectives and the means to attain them, and alternatives in the event that preferred options fail.

Key Considerations

Whether, where, when, and how to intervene militarily pose problems that call for subjective judgments. Secretary Weinberger prescribed "six major tests to be applied when we are weighing the use of US combat forces abroad": the presence of "vital" US or allied interests; clear intent to win; precise objectives and ways to accomplish them; "reasonable" assurance of public support; military action as a last resort; continual reassessment and adjustments as events unfold. The considerations identified below, unlike Weinberger's preconditions, recognize that there are no immutable and universally applicable rules for decisions about interventions. Each case is unique. The following checklists therefore pose questions rather than answers.

National Interests

Military intervention in the absence of highly valued interests often is difficult to justify. Interests that directly affect US national security normally take precedence over all others. The only vital interest is national survival with sovereignty, territorial integrity, fundamental institutions, and values acceptably intact. Other valid interests, including traditional life styles and concerns for international order, are worth preserving. The advisability of military action is most evident when practical political or economic interests are strong. International interests in petroleum, for example, helped create a potent coalition after Iraq invaded Kuwait in 1990, whereas mainly humanitarian motives thus far have failed to solidify unilateral US or multilateral support for military intervention in Bosnia-Herzegovina. Intangible interests nevertheless may sometimes prove compelling. National credibility, a necessary asset for any nation that wants to lead, is among them.

A checklist that connects national interests with military intervention might typically include the following entries:

Threats to National Interests

Threats to valued national interests vary with regard to imminence and intensity. Decisionmakers who hope to avoid wrong wars at wrong times with wrong enemies cannot rationally conclude that military initiatives would be best until they consider alternatives, appraise probable risks, and prioritize each threat. Those processes first demand intelligence estimates that evaluate enemy capabilities, limitations, and potential responses to US options, supplemented by net assessments that dispassionately compare friendly and enemy postures, with particular attention to geographical contexts.

A checklist that connects threats with military intervention might typically include the following entries:

Political Aims and Military Missions

Political aims and military missions prescribe for US armed forces what must be done to safeguard national interests against perceived threats. Like interests, they should be prioritized to allow the application of resources for the most important purposes. Explicit statements are commendable, because unrealistic tasks and speculative requirements otherwise result. Political aims and military missions are best developed in collaboration to ensure compatibility; the US experience in Vietnam, for example, was adversely influenced by senior commanders and their civilian superiors who pursued incompatible outcomes. While it is a truism that no plan survives contact, decisionmakers must nevertheless guard against so-called "mission creep," which incrementally (sometimes inadvertently) amplifies ends well beyond the original intent of a plan and hence the ways and means available to attain them. Humanitarian purposes, for example, initially inspired US operations in Somalia; the subsequent switch to peacemaking and nation development opened a gulf between goals and deployed capabilities. Disputes among the United States, the United Nations, NATO, and other allies can be dangerously disruptive if unresolved, as in Bosnia where some prefer peacekeeping while others believe peace enforcement should be the main goal.

Desirable objectives seek a better situation than prevailed before US armed forces intervened. Military victory is only one satisfactory end, despite General MacArthur's admonition that there is no substitute for it. As defined in this article, success is attained if the United States achieves sound objectives in acceptable time at acceptable costs.

A checklist that connects political aims and military missions with military intervention might typically include the following entries:

Strategic and Policy Guidance

Strategic and policy guidance, including military rules of engagement, can simplify or complicate the preparation of plans and the attainment of objectives. US policymakers were relatively unconcerned about damage and enemy casualties during World War II, because unconditional surrender was the goal in a "total war" and our principal allies were fighting for survival. US leaders, in sharp contrast, imposed strict restrictions on military operations throughout the Cold War to reduce the likelihood of a nuclear showdown with the Soviet Union. Manchuria remained a "privileged sanctuary" while combat raged in Korea. President Kennedy and Secretary of Defense McNamara personally directed US naval blockades during the Cuban missile crisis. Restraints tightened to prevent a wider war after US forces intervened massively in Vietnam. Sanctuaries in Laos and Cambodia were long off limits to US forces; President Johnson picked many targets; graduated responses seemed to apply military power grudgingly. US policymakers, most prominently since Desert Storm, have been reluctant to engage in any armed conflict that promises to be protracted, cause even a few US casualties, or endanger noncombatants. They are prone to consider force only as a last resort, although early decisive action occasionally might quell incipient crises before they become intractable.

A checklist that connects strategic and policy guidance with military intervention might typically include the following entries:

Planning Options

US national security planners balance interests and capabilities against risks and costs, taking policy guidance into account, as they search for feasible, suitable, flexible, and politically acceptable solutions to intervention problems. They advise decisionmakers about the relative roles that diplomacy and military power should play, which missions US armed forces might most appropriately perform, and which might better be left to allies. DOD routinely prepares contingency plans to avoid injurious surprise if crises erupt on short notice, but since precise circumstances are unpredictable, planners cannot anticipate every eventuality. Prior planning nevertheless enables senior officials to reach sound broad conclusions about military intervention much sooner than starting from scratch.

Rear Admiral J. C. Wylie, in his treatise entitled Military Strategy, identified "planning for certitude as the greatest of all military mistakes."[4] Judicious planners consequently ask themselves "What if this or that happens?" and carefully consider alternative courses of action even when response times are short, then devise substitute Options B, C, and D for implementation if preferred Option A is precluded or fails to produce expected results. One school of thought contends that no action at all is preferable to interventions that risk failure, because accompanying costs would be too high. George Shultz, when he was Secretary of State, spoke for a second school whose members believe that appeasement may invite aggression; that the United States is morally obligated to assist allies with whom it has security commitments; and that it "must bear responsibility for the consequences of its inaction. . . . We cannot opt out of every contest," he continued. "If we do, the world's future will be determined by others--most likely by those who are . . . most hostile to our deeply held principles."[5]

A checklist that connects planning options with military intervention might typically include the following entries:


Competition for scarce resources always is fierce, but the best laid plans are useful only if ends (specified as desired outcomes) and means (forces and funds) match reasonably well, with enough in reserve to cope if other current threats loom large. Shortfalls create risks. Reconciliations are required whenever the military balance becomes so unfavorable that important US interests appear vulnerable, objectives appear unrealistic, and commanders anticipate excessively high casualties. Improvements then await decisions to reduce ambitions, add assets, or both.

Repeated operations not directly related to US security, though of value, may expend so much of our operations and maintenance (O&M) funds that little is left to invest in future readiness. The choice then is to cut commitments, increase resources, or both. Multilateral participation might be imperative, although allies and coalitions often impose constraints and require a political or economic quid pro quo.

A checklist that connects resources with military intervention might typically include the following entries:

Congressional and Public Support

The extent of popular and congressional support ideally should be clear before we undertake a military intervention, but that may not always be the case. Circumstances could force action before approval can be determined; approval also could prove to be transitory. The Tonkin Gulf Resolution of 10 August 1964, which endorsed intervention in Vietnam, received only two dissenting votes in Congress, but enthusiasm faded fast after the Tet offensive in 1968. The task of statesmanship therefore is to develop and sustain support for foreign policy initiatives that will involve armed intervention. Compelling interests, sensible objectives, and reasonable prospects for success usually are required to sustain the opinion of the American people and US allies.

The news media exerts a powerful influence on US and world opinion by deciding which crises to publicize and which to ignore. Real-time pictures of starving Somali children, for example, helped spur decisions to intervene, while famine in inaccessible Sudan still receives scant notice.

A checklist that connects public opinion with military intervention might typically include the following entries:


Military intervention operations, no matter how innocuously they begin, may eventually make US soldiers, Marines, sailors, and airmen lay their lives on the line. The President, Congress, and their advisers therefore would be wise to repeatedly scrutinize pertinent national interests, threats, objectives, policies, plans, resources, public opinion, and priorities before and after military intervention begins to ascertain whether corrective actions are required. A composite checklist comparable in function to those in this article could assist such assessments.


1. Media response to Weinberger's "tests" is available in Secretary Weinberger's National Press Club Speech, Washington, Current News Special Edition No. 1244, DOD, 8 January 1985. That speech plus nine other official views are reproduced in Stephen Daggett and Nina Serafino, The Use of Force: Key Contemporary Documents, Rpt. Nr. 94-805F, Washington, Congressional Research Service, 17 October 1994.

2. For some contemporary points and counterpoints, see US Congress, House Rept. 104-18, Parts 1, 2, 3, National Security Revitalization Act, Report Together With Additional and Dissenting Views, 104th Congress, 1st Session, 6 February 1995, 166 p.; Ann Devroy, "President, Dole Divide Over Foreign Policy," The Washington Post, 2 March 1995, p. 1; Senator Bob Dole, "Shaping America's Global Future," Foreign Policy, No. 98 (Spring 1995), 29-43.

3. Past practices are summarized by Mark M. Lowenthal and Robert L. Goldich in Use of Force by the United States: Case Studies, 1950-1991, Rpt. Nr. 92-757, Washington, Congressional Research Service, 14 October 1992. Stanley R. Sloan analyzes present trends in The United States and the Use of Force in the Post-Cold War World: Toward Self-Deterrence?, CRS Rpt. Nr. 94-581S, 20 July 1994.

4. J. C. Wylie, Military Strategy: A General Theory of Power Control (New Brunswick, N.J.: Rutgers Univ. Press, 1967), p. 85.

5. "Shultz vs. Weinberger--When to Use Power," U.S. News & World Report, 24 December 1984, pp. 20-21.

John M. Collins is the Senior Specialist in National Defense with the Congressional Research Service of the Library of Congress. He enlisted in the Army as a private in 1942 and retired with the rank of colonel in 1972. He is a graduate of the University of Kansas City and holds a master's degree from Clark University, Worcester, Massachusetts. He is also a graduate of the Army Command General Staff College, the Armed Forces Staff College, the Industrial College of the Armed Forces, and the National War College. He was chief of the Campaign Planning Group, Vietnam, in 1967-68. He is the author of ten books, including Grand Strategy: Principles and Practices (Naval Institute Press, 1973), and many major Library of Congress publications.

Reviewed 25 November 1996. Please send comments or corrections to