Case Study 1: The U.S. Response to the Russia–Ukraine War, 2022–2026

The case

On February 24, 2022, Russia launched a large-scale invasion of Ukraine. The United States and most of its NATO allies responded with the largest combination of sanctions and military aid since the end of the Cold War. The case is unusual in that it has run, as of early 2026, for nearly four years through three U.S. presidencies (the late Biden, the Trump-2, and arguably Trump-1's residual policy framework that shaped the first weeks of the conflict). It has tracked a marked shift in American partisan alignment on the war. And it has tested every one of the foreign-policy traditions described in this chapter against a real conflict, with real costs, in real time.

This case study walks through the chronology, the major American policy decisions, the partisan polarization that emerged, and the steel-manned positions of the principal traditions on what the United States should do.

Chronology, in summary

Pre-invasion (late 2021–February 2022). Russian troop buildup along Ukraine's borders. The Biden administration declassified intelligence about the invasion plans publicly — an unusual step, designed both to warn Kyiv and to deny Russia surprise. Diplomatic efforts continued through January and February; they did not succeed.

Invasion and initial response (February–March 2022). Russia launched a multi-axis invasion. The expected rapid Russian victory did not materialize; Ukrainian resistance held Kyiv and reversed the Russian advance in the north. The U.S. and EU imposed unprecedented sanctions: asset freezes on the Russian central bank's reserves overseas (~$300 billion), exclusion of major Russian banks from SWIFT, restrictions on energy-sector transactions, and sweeping export controls. Initial U.S. weapons transfers focused on man-portable systems (Javelin anti-tank, Stinger anti-aircraft).

Phase 2 — the long war (mid-2022 through 2024). Ukrainian counteroffensives in fall 2022 (recapturing Kharkiv region and Kherson) gave way to attritional combat in the Donbas. U.S. weapons transfers escalated through successive thresholds: HIMARS rocket systems (mid-2022), more advanced air defense (Patriot, mid-2022 to 2023), main battle tanks (Abrams, decision early 2023), F-16 fighter jets (decision mid-2023, deliveries beginning 2024), longer-range ATACMS missiles (decision late 2023 / early 2024). Each escalation was preceded by months of internal debate over escalation risks.

By 2024, total U.S. appropriations for Ukraine support exceeded $175 billion combined (military, economic, and humanitarian). The pace of new appropriations slowed as the partisan polarization (described below) hardened.

Partisan polarization (2023–2024). Initial public support for Ukraine aid was overwhelmingly bipartisan in February–March 2022. By 2023, a growing share of Republican voters and officials questioned the open-ended commitment. By 2024, the partisan split had widened: Pew Research surveys showed Democratic support for Ukraine aid stable in the 60–70 percent range while Republican support declined into the 30s. Republican congressional dynamics shifted accordingly: a House Republican faction (sometimes called the "Ukraine skeptics") held up additional aid packages for months; the eventual passage of the April 2024 aid package required Speaker Mike Johnson's coordination with Democrats and a discharge-petition threat.

The Trump-2 transition (January 2025–present). Trump-2 entered office with an explicit position that the war should end through negotiation, that U.S. open-ended support was not sustainable, and that pressure on both Russia and Ukraine to negotiate was warranted. The administration's actions in 2025 included reduction of certain forms of military aid; conditional approaches to additional support tied to Ukrainian willingness to negotiate; direct U.S.-Russia diplomatic engagement; and significant pressure on European NATO members to take primary responsibility for Ukrainian support.

European response: substantial increases in defense spending across most NATO members, expansion of European weapons transfers to Ukraine, and at the same time difficulty matching the scale of the U.S. role. The shape of any negotiated settlement remains uncertain as of early 2026.

The American positions, steel-manned

The case has revealed how the foreign-policy traditions discussed in the chapter map onto a real, ongoing conflict. Each tradition's position is presented in its strongest form below.

The liberal-internationalist position

The strongest version: Russia's invasion was a frontal assault on the most fundamental principle of the post-1945 order — that borders cannot be redrawn by force. Letting it succeed would invite further aggression by Russia (against the Baltics, Moldova, Georgia) and signal to other revisionist powers (most importantly China, observing Taiwan) that aggression pays. U.S. support for Ukraine has been the most cost-effective deterrent strategy in modern history: at less than 5 percent of the U.S. defense budget, it has degraded the conventional military of America's second-largest nuclear adversary without putting American troops in combat. The aid has revitalized the U.S. defense industrial base after years of underinvestment. Continuing support is in U.S. interests; abandoning Ukraine would damage U.S. credibility with allies in Europe and the Indo-Pacific, embolden Russia, and undermine the post-1945 architecture that has produced eight decades of great-power peace.

Leading proponents in 2022–2025 included most of the establishment foreign-policy commentariat, the bipartisan congressional Ukraine caucus (including Senators Lindsey Graham, Mitch McConnell on the Republican side; Senators Sheldon Whitehouse, Richard Blumenthal on the Democratic side), and most of the establishment think tanks (Brookings, CFR, CNAS).

The realist position

The strongest version: The war is in a geographic theater where Russia has more vital interests than the United States. NATO expansion to Russia's borders contributed to (though did not justify) Russian aggression — a point Mearsheimer and others made before 2022 and have continued to make since. The risks of escalation, including nuclear escalation, are non-trivial; Russia has explicit nuclear doctrine that contemplates use in defense of "the territorial integrity of the Russian Federation," and parts of occupied Ukraine have been formally annexed. Europe should bear the primary burden of supporting Ukraine; America's primary theater is the Indo-Pacific, and resources spent on Ukraine are not available for Pacific contingencies. A negotiated settlement, even on terms unfavorable to Ukraine, is preferable to indefinite war that Ukraine cannot win on the battlefield. U.S. support should be calibrated to push toward negotiation, not to prevent it.

Leading proponents: John Mearsheimer, Stephen Walt, Stephen Wertheim, the Quincy Institute. Some elements of this argument have also been made by Elbridge Colby — though his version is grounded primarily in prioritization (Pacific over Europe) rather than in skepticism of the underlying U.S. interest.

The progressive position

The strongest version: Genuinely sympathetic to Ukraine's sovereignty and to the human costs of Russian aggression. Skeptical of the speed and scale of weapons-transfer authorities, the influence of defense contractors in shaping the response, and the corruption risks in large weapons-transfer programs. Concerned that the absence of meaningful diplomatic alternatives early in the war foreclosed possibilities that might have ended the killing sooner. Supportive of humanitarian aid; more cautious about open-ended military commitments. Concerned about the economic costs of sanctions — particularly food and energy price increases that have hit poorer countries hardest. Sees a tension between the moral case for supporting Ukraine and the practical concern that an attritional war is destroying Ukraine in order to "save" it.

Leading proponents: progressive members of Congress (with substantial variation; some have been strong Ukraine supporters), Matt Duss, elements of the Quincy Institute, Jacobin and similar publications.

The "America First" position

The strongest version: The war is a European problem; Europe should pay for its own defense. The United States has spent enormous sums on a war that does not affect U.S. vital interests directly; the China challenge demands those resources, and U.S. munitions stockpiles have been depleted in ways that complicate Pacific contingencies. A negotiated settlement that ends the killing is preferable to a long war that bleeds Ukraine, hardens Russia, and depletes U.S. capabilities. The post-Cold War assumption that the United States should automatically guarantee European security at American expense was a 1990s policy choice, not an iron law; it should be revisited.

Leading proponents: J.D. Vance (before becoming Vice President), elements of American Conservative and Compact, Sumantra Maitra ("dormant NATO"), Curt Mills.

The position the Biden administration actually took

Combination of liberal-internationalist framing (defending the rules-based order) with constraint on escalation (gradual rather than maximalist weapons transfers; declassified intelligence to deny surprise; coordination with European allies). The administration deferred or denied certain Ukrainian requests (long-range strikes inside Russia, more aggressive nuclear-energy posture) that risked escalation. Critics on the right argued this was insufficient resolve; critics on the left argued the cumulative escalation amounted to drift toward a war without a clear endpoint.

The position the Trump-2 administration actually took

A push toward negotiation, premised on the view that the war was no longer winnable on battlefield terms favorable to Ukraine and that continued U.S. funding was politically and strategically unsustainable. Conditioning of further support on Ukrainian willingness to negotiate. Direct diplomatic engagement with Russia. Pressure on European NATO members to take over the primary support role. Critics on the liberal-internationalist side argued this was capitulation; supporters argued it was overdue realism about what the war could achieve and what the United States could afford.

What the case illustrates

A few takeaways.

First, foreign-policy positions are not always partisan. In 2022, support for Ukraine spanned both parties; opposition came from a small minority on each end. By 2025, the partisan split was much sharper — but it was a recent partisan split, driven significantly by elite cues (President Trump and J.D. Vance's stated positions; the Republican congressional caucus's evolution) rather than by long-standing party doctrine.

Second, the same conclusion can be supported by different traditions. Senators who argued for sustained Ukraine aid included liberal internationalists (citing the rules-based order), neoconservatives (citing democracy promotion and U.S. primacy), and even some realists (citing the strategic value of degrading Russian conventional military capability at relatively low U.S. cost). Senators who argued for ending the war or shifting the burden included realists (citing escalation risks and theater priorities), "America First" nationalists (citing burden-sharing and Pacific reorientation), and progressives (citing humanitarian costs and the absence of an end-state). Neither side was monolithic.

Third, escalation management is a live problem. Each weapons-transfer threshold (HIMARS, Patriot, Abrams, F-16, ATACMS) was preceded by months of debate about whether the transfer would cross a Russian "red line." None did, in the sense that Russia did not retaliate against NATO directly. But the iterative nature of the escalation — and the cumulative degradation of Russian conventional capability — makes evaluation of the policy difficult. Did each threshold succeed because deterrence held, or because the Russian "red lines" were never as firm as worry-cases suggested? The answer matters for how the United States handles future escalation decisions.

Fourth, the policy debate is not over, and reasonable people disagree. As of early 2026, the eventual outcome of the war and the eventual judgment on U.S. policy remain unsettled. Citizens engaging with the debate are well advised to read across traditions, identify which arguments rest on factual claims (which can be checked against evidence) and which rest on normative claims (which depend on what one believes the United States is for in the world), and resist the temptation to assume one's own tribe's position is the only defensible one. On Ukraine, as on most foreign-policy questions, more than one defensible position exists — and the disagreement is real, substantive, and worth taking seriously.

Continued in Case Study 2, which examines the American policy debate around the Israel-Gaza war (2023–2026) using the same steel-manning discipline.