Grand strategy
World War II: An example of modern grand strategy is the decision of the Allies in World War II to concentrate on the defeat of Germany first. The decision, a joint agreement made after the attack on Pearl Harbor (1941) had drawn the US into the war, was a sensible one in that Germany was the most powerful member of the Axis, and directly threatened the existence of the United Kingdom and the Soviet Union. Conversely, while Japan's conquests garnered considerable public attention, they were mostly in colonial areas deemed less essential by planners and policy-makers. The specifics of Allied military strategy in the Pacific War were therefore shaped by the lesser resources made available to the theatre commanders.

Cold War: The US and the UK used a policy of containment as part of their grand strategy during the Cold War.

In the United States: The conversation around grand strategy in the United States has evolved significantly since the country's founding, with the nation shifting from a strategy of continental expansion, isolation from European conflicts, and opposition to European empires in the Western hemisphere in its first century, to a major debate about the acquisition of an empire in the 1890s (culminating in the conquest of the Philippines and Cuba during the Spanish–American War), followed by rapid shifts between offshore balancing, liberal internationalism, and isolationism around the world wars. The Cold War saw increasing use of deep, onshore engagement strategies (including the creation of a number of permanent alliances, significant involvement in other states' internal politics, and a major counterinsurgency war in Vietnam.) With the end of the Cold War, an early strategic debate eventually coalesced into a strategy of primacy, culminating in the invasion of Iraq in 2003. The aftershocks of this war, along with an economic downturn, rising national debt, and deepening political gridlock, have led to a renewed strategic debate, centered on two major schools of thought: primacy and restraint. A return to offshore balancing has also been proposed by prominent political scientists Stephen Walt and John Mearsheimer.

In the 1990s: The end of the Cold War and the collapse of the Soviet Union removed the focal point of U.S. strategy: containing the Soviet Union. A major debate emerged about the future direction of U.S. foreign policy. In a 1997 article, Barry R. Posen and Andrew L. Ross identified four major grand strategic alternatives in the debate:

neo-isolationism
selective engagement
cooperative security
primacy

Neo-isolationism: Stemming from a defensive realist understanding of international politics, what the authors call "neo-isolationism" advocates the United States remove itself from active participation in international politics in order to maintain its national security. It holds that because there are no threats to the American homeland, the United States does not need to intervene abroad. Stressing a particular understanding of nuclear weapons, the authors describe how proponents believe the destructive power of nuclear weapons and retaliatory potential of the United States assure the political sovereignty and territorial integrity of the United States, while the proliferation of such weapons to countries like Britain, France, China and Russia prevents the emergence of any competing hegemon on the Eurasian landmass. The United States' security and the absence of threats means that "national defense will seldom justify intervention abroad." Even further, its proponents argue that "the United States is not responsible for, and cannot afford the costs of, maintaining world order." They also believe that "the pursuit of economic well-being is best left to the private sector," and that the United States should not attempt to spread its values because doing so increases resentment towards the U.S. and in turn, decreases its security. In short, neo-isolationism advises the United States to preserve its freedom of action and strategic independence.
In more practical terms, the authors discuss how the implementation of a so-called "neo-isolationist" grand strategy would involve less focus on the issue of nuclear proliferation, withdrawal from NATO, and major cuts to the United States military presence abroad. The authors see a military force structure that prioritizes a secure nuclear second-strike capability, intelligence, naval and special operations forces while limiting the forward-deployment of forces to Europe and Asia.
Posen and Ross identify such prominent scholars and political figures as Earl Ravenal, Patrick Buchanan and Doug Bandow.

Selective engagement: With similar roots in the realist tradition of international relations, selective engagement advocates that the United States should intervene in regions of the world only if they directly affect its security and prosperity. The focus, therefore, lies on those powers with significant industrial and military potential and the prevention of war amongst those states. Most proponents of this strategy believe Europe, Asia and the Middle East matter most to the United States. Europe and Asia contain the great powers, which have the greatest military and economic impact on international politics, and the Middle East is a primary source of oil for much of the developed world. In addition to these more particular concerns, selective engagement also focuses on preventing nuclear proliferation and any conflict that could lead to a great power war, but provides no clear guidelines for humanitarian interventions.
The authors envision that a strategy of selective engagement would involve a strong nuclear deterrent with a force structure capable of fighting two regional wars, each through some combination of ground, air and sea forces complemented with forces from a regional ally. They question, however, whether such a policy could garner sustained support from a liberal democracy experienced with a moralistic approach to international relations, whether the United States could successfully differentiate necessary versus unnecessary engagement and whether a strategy that focuses on Europe, Asia and the Middle East actually represents a shift from current engagement.
In the piece, Barry Posen classified himself as a "selective engagement" advocate, with the caveat that the United States should not only act to reduce the likelihood of great power war, but also oppose the rise of a Eurasian hegemon capable of threatening the United States.
Robert J. Art argues that selective engagement is the best strategy for the twenty-first century because it is, by definition, selective. "It steers the middle course between an isolationist, unilateralist course, on the one hand, and world policeman, highly interventionist role, on the other." Therefore, Art, concludes, it avoids both overly restrictive and overly expansive definitions of U.S. interests, finding instead a compromise between doing too much and too little militarily. Additionally, selective engagement is the best strategy for achieving both realist goals—preventing WMD terrorism, maintaining great power peace, and securing the supply of oil; and liberal goals—preserving free trade, spreading democracy, observing human rights, and minimizing the impact of climate change. The realist goals represent vital interests and the liberal goals represent desirable interests. Desirable interests are not unimportant, Art maintains, but they are of lesser importance when a trade-off between them and vital interests must be made.  Selective engagement, however, mitigates the effect of the trade-off precisely because it is a moderate, strategic policy.

Cooperative security: The authors write "the most important distinguishing feature of cooperative security is the proposition that peace is effectively indivisible." Unlike the other three alternatives, cooperative security draws upon liberalism as well as realism in its approach to international relations. Stressing the importance of world peace and international cooperation, the view supposes the growth in democratic governance and the use of international institutions will hopefully overcome the security dilemma and deter interstate conflict. Posen and Ross propose that collective action is the most effective means of preventing potential state and non-state aggressors from threatening other states. Cooperative security considers nuclear proliferation, regional conflicts and humanitarian crises to be major interests of the United States.
The authors imagine that such a grand strategy would involve stronger support for international institutions, agreements, and the frequent use of force for humanitarian purposes. Were international institutions to ultimately entail the deployment of a multinational force, the authors suppose the United States' contribution would emphasize command, control, communications and intelligence, defense suppression, and precision-guided munitions-what they considered at the time to be the United States' comparative advantage in aerospace power. Collective action problems, the problems of the effective formation of international institutions, the vacillating feelings of democratic populations, and the limitations of arms control are all offered by the authors as noted criticisms of collective security.

Primacy: Primacy is a grand strategy with four parts:

Military preponderance
Reassurances and containment of allies
Integration of other states into US-designed institutions
Limits to the spread of nuclear weapons
As a result, it advocates that the United States pursue ultimate hegemony and dominate the international system economically, politically and militarily, rejecting any return to bipolarity or multipolarity and preventing the emergence of any peer competitor. Therefore, its proponents argue that U.S. foreign policy should focus on maintaining U.S. power and preventing any other power from becoming a serious challenger to the United States. With this in mind, some supporters of this strategy argue that the U.S. should work to contain China and other competitors rather than engage them. In regards to humanitarian crises and regional conflicts, primacy holds that the U.S. should only intervene when they directly impact national security, more along the lines of selective engagement than collective security. It does, however, advocate for the active prevention of nuclear proliferation at a level similar to collective security.
Implementation of such a strategy would entail military forces at similar levels to those during the Cold War, with emphasis on military modernization and research and development. They note, however, that "the quest for primacy is likely to prove futile for five reasons": the diffusion of economic and technological capabilities, interstate balancing against the United States, the danger that hegemonic leadership will fatally undermine valuable multilateral institutions, the feasibility of preventive war and the dangers of imperial overstretch.