Washington is littered with the corpses of grand plans to restore the Merchant Marine. The Trump administration’s Maritime Action Plan is the latest attempt, and to its credit, the most comprehensive since World War II.
The plan is the government’s blueprint to resurrect America’s commercial shipping and domestic shipbuilding industry. The goal is straightforward: build enough merchant ships and train enough civilian mariners to sustain the military through war, while cutting reliance on foreign supply chains in peace. With a $1.5 billion Maritime Security Trust Fund, Maritime Prosperity Zones, and fees on foreign-built vessels, it treats over a half-century of decline as the crisis it is.
But the Maritime Action Plan repeats the mistake that sank its predecessors: It assembles the tools to rebuild the fleet without ever defining what the rebuilt fleet looks like. The Navy can tell you it operates 291 battle force ships against a 355-ship floor and a new plan to reach 450. Ask how many merchant ships and mariners the nation needs to sustain that fleet in peace and war, and there is no number, no target, and no benchmark.
Without a measure of success, an attempted reform like the Maritime Action Plan is another budget line waiting to stagnate. If Washington is serious about reversing maritime decline, it should anchor the Maritime Action Plan to hard targets. Adopt the Mahan ratio — a nation’s merchant fleet divided by its naval ships — as the Maritime Action Plan’s yardstick: Set a mandated ratio on a fixed deadline, tie Trust Fund and cargo preference dollars to automatic triggers when the fleet falls behind, and count the drone vessels the Navy is betting on toward the total. Only then does a list of funding proposals and congressional actions become a measurable strategy for putting hulls in the water.
Enter what I call the Mahan ratio: a simple but powerful metric that can turn the Maritime Action Plan’s ambitions into trackable progress. By dividing a nation’s merchant fleet by its naval ships, the ratio reveals whether a country pursues genuine sea power — and thereby global influence — or just naval power.
The Mahan ratio counts vessels because presence and strategic reach define maritime power as much as raw cargo capacity does. Vessel count also provides the transparency and consistency that sustained policy accountability requires.
This ratio is named for Alfred Thayer Mahan, the naval theorist whose 1890 work The Influence of Sea Power Upon History shaped American maritime military strategy for generations. But Mahan’s core insight has been systematically misunderstood. Policymakers fixated on his call for a powerful navy but ignored his equally emphatic argument: Naval power without commercial shipping is unsustainable.
“Sea power,” Mahan wrote, “includes not only the military strength afloat … but also the peaceful commerce and shipping from which alone a military fleet naturally and healthfully springs, and on which it securely rests.” True sea power requires balance: combat vessels to protect trade and merchant ships to generate the wealth that sustains military power. America spent the 20th century building one pillar while letting the other crumble.
The Mahan Ratio and Maritime Imbalance
Direct comparisons of American and Chinese maritime fleets involve methodological challenges. For the U.S. merchant fleet, this analysis uses Maritime Administration data for U.S.-flagged vessels engaged in international trade. For China, it uses vessels owned by China sailing under Chinese flag, including Hong Kong. On the naval side, U.S. figures include auxiliary and support ships, while Chinese naval data excludes them. As the Congressional Research Service has noted, such differences can create an “apples-vs.-oranges” comparison, but changes over time in these comparisons can be valuable in understanding trends of competing fleets. The same logic applies: The strategic trends revealed by the Mahan ratio remain meaningful.
No single metric can capture the full complexity of maritime power, and the Mahan ratio is no exception. It does not measure vessel capability, ownership structure, strategic lift potential, or operational control. A Panamax container ship is not equivalent to a tanker optimized for military sealift, and a Chinese-owned fleet dispersed across global trade routes does not equate to assured wartime logistics capacity. The ratio captures the critical balance Mahan identified — whether a nation maintains the commercial foundation necessary to sustain naval power over time.
As a directional metric, the Mahan ratio reveals strategic trends that tonnage figures, capability indices, and naval rankings miss.
Figure 1: The Collapse of American Maritime Balance. America’s Mahan ratio has collapsed from 6.00 in 1920 to just 0.64, while China’s has surged from 2.72 in 1990 to 20.31 in 2025.
The directional findings are clear: In 1950, fresh off World War II victory, America’s Mahan ratio stood at 5.31, an optimal balance of 3,364 merchant vessels and 634 active naval ships that enabled the United States to project power globally while sustaining military operations and economic influence worldwide. During the Korean War, with the ratio at 5.31, nearly 500 commercial vessels carried 85 percent of dry cargo to the Korean Peninsula with minimal strain.
By the Gulf War in 1991, the ratio had collapsed to 1.12. The Department of Defense acknowledged the consequences in a report to Congress on the conduct of the war: The Ready Reserve Force was unprepared, fast sealift capability was insufficient, and nearly half the sealift relied on foreign-flagged vessels. The operation succeeded only because the United States had nearly six months to build forces, faced no sea lane interdiction, and enjoyed unprecedented coalition support — conditions that cannot be assumed in a future Pacific conflict.
By 2025, the collapse was complete: 188 merchant ships supporting 293 active naval ships — the broader count this analysis uses, including auxiliary and support ships, as described above — for a ratio of just 0.64, statistically identical to the 0.65 produced by the Navy’s official 291-ship battle force total in 2026. The United States has built the most capable combat fleet in history and let the commercial foundation Mahan understood as essential to national power collapse. The Navy has not even held its battle force steady — 295 ships in late 2024, 291 today — even as its shipbuilding budget climbed and its new plan promises 450. The merchant half has no target at all.
The pattern is consistent: When the ratio exceeded 3.0, the United States possessed the commercial foundation to sustain military operations at scale. When it fell below that threshold, as in the Gulf War, strategic flexibility depended on conditions America could not control.
China has spent two decades building the balance America let lapse. Since 2005, Beijing has deliberately grown both fleets in tandem: its naval fleet expanding 78.7 percent from 221 vessels to 395 while its merchant fleet grew 307.5 percent from 1,969 ships to 8,022. The parallel growth is deliberate. Chinese military writings explicitly reference Mahanian principles, arguing that “sea power ought to give priority to the maritime economy” and that control of sea lanes requires both naval forces and commercial presence. The Maritime Silk Road, with its network of Chinese-invested ports, is an instrument for projecting commercial maritime dominance backed by naval power.
China’s ratio of 20.31 demonstrates Beijing’s understanding that sea power requires a commercial foundation as much as warships. It is a strategic reality that Washington has yet to relearn.
Table 1: U.S. and China Fleet Compositions and Mahan ratio, 1920-2025.
Three Measures for Accountability
This is where the Maritime Action Plan’s ambitious proposals meet harsh reality. The plan calls for establishing a Strategic Commercial Fleet, expanding cargo preference requirements, creating shipyard incentive programs, and training thousands more credentialed mariners. These are necessary steps, but without a clear accountability framework, how will policymakers know if the steps are working? How will Congress evaluate whether the Maritime Security Trust Fund’s $1.5 billion is delivering results? How will defense planners assess whether sealift gaps are actually closing?
The Mahan ratio provides that framework. It offers a single, historically validated metric that captures the essence of maritime power: the balance between commercial and combat capability. The Maritime Action Plan should adopt three concrete measures to operationalize it.
First, establish target ratios with timelines. Because the Navy’s new shipbuilding plan grows the fleet toward 450 ships, the merchant fleet bar rises with it. An interim ratio of 1.0 by 2035 would require the U.S.-flagged fleet to expand from 188 vessels to roughly match a 450-ship navy. A long-term ratio of 3.0 by 2045 would demand on the order of 1,350 merchant vessels. The Golden Fleet makes the commercial buildout more urgent: Every warship added raises the number of merchant hulls required to keep sea power in balance.
Second, tie reporting to budgetary triggers. The Maritime Administration should calculate and publish the U.S. Mahan ratio annually, alongside comparisons with peer competitors. Reporting creates accountability only if it has teeth. Congress should establish automatic mechanisms tied to the Maritime Action Plan’s Maritime Security Trust Fund. For example, if the ratio fails to reach 1.0 by 2035, Trust Fund disbursements to domestic shipbuilding incentive programs automatically increase by a defined percentage, and the White House Office of Management and Budget should submit a correction plan within 90 days.
Shipbuilding milestones should carry equal weight. If domestic shipyard capacity fails to meet defined annual vessel production targets, the Maritime Action Plan’s shipbuilding incentive programs should automatically trigger additional funding and support for the following year.
If the ratio is trending backward, cargo preference requirements should automatically expand. As the Maritime Administration Administrator Stephen Carmel recently noted, cargo preference is critical to sustaining the U.S.-flagged fleet right now. Tying its expansion to Mahan ratio performance puts that policy lever on automatic, beyond the reach of annual politics. The ratio becomes a policy trigger in its own right. If it falls or flatlines, reforms accelerate automatically without waiting for the next budget cycle.
Third, integrate unmanned systems strategically. The Navy’s May 2026 shipbuilding plan now places drone systems at the center of the future fleet: 47 medium surface drones and 16 subsurface drones by 2031, organized under a formal “hedge force concept.” That makes counting them rigorously a near-term necessity.
These platforms should count toward the Mahan ratio calculation, but with clear standards. A drone container ship should count as a merchant vessel. A drone surveillance platform might count as a fraction of a naval vessel, reflecting its lower capability compared to crewed warships. This keeps the ratio tied to actual maritime capacity and rewards the technological edge that could help America compete with China’s numerical advantage.
The drone dimension is crucial. China doesn’t need to match America’s naval technology ship for ship. Its merchant fleet gives it presence, influence, surveillance, and logistics capacity that pure naval power cannot replicate. American drone systems could partially offset China’s merchant advantage at lower cost, extending reach across contested waters and easing the load on crewed hulls. This will only work if the United States measures and tracks this capability systematically.
The Strategic Stakes
Critics might contend that achieving a ratio of 3.0 is financially impossible, requiring massive subsidies for an industry that can’t compete with foreign shipbuilding. But this argument concedes defeat before the battle begins. The Maritime Action Plan proposes exactly the kind of interventions designed to make domestic shipbuilding competitive. The question is whether these interventions will be sustained and measured. Without the Mahan ratio, the United States won’t know if it’s making progress or just making promises.
China’s Mahan ratio of 20.31 is a statement of grand strategy. Beijing understands that maritime dominance requires both the warships to control sea lanes and the merchant vessels to exploit them economically. China’s network of Maritime Silk Road initiative, shipbuilding capacity that dwarfs America’s, and 1.7 million seafarers compared to America’s 12,000 form a coherent Mahanian strategy to achieve sea power while America pursued only naval power.
The Maritime Action Plan represents a genuine opportunity to reverse this trajectory, but without accountability measures, grand strategies become grand disappointments. America’s comprehensive maritime policies of the early 20th century worked for a while, and then America stopped measuring, stopped caring, and stopped competing. The result is a merchant fleet that’s 1 percent of global capacity despite America representing 25 percent of global gross domestic product.
Balanced maritime power carried the United States through two world wars and underwrote the rules-based international order it built afterward. As that balance eroded, other nations moved into the space America vacated in global shipping, a space China has filled over the past two decades.
Congress should mandate Mahan ratio reporting as part of the Maritime Action Plan’s implementation, with binding targets, automatic budgetary triggers, and annual assessments. These goals are derived from historical periods when American sea power translated into global influence and economic prosperity. The alternative is clear: more decades of drift, more ships built in Chinese yards, more trade carried on foreign hulls, and more strategic vulnerability dressed up as fiscal prudence.
Alfred Thayer Mahan understood 136 years ago what Beijing understands today: Sea power is the integration of commercial and combat maritime strength. The Mahan ratio offers a way to measure whether America is relearning that lesson or continuing to ignore it.
Ander Heiles is a surface warfare officer in the U.S. Navy, licensed merchant mariner, and a 2025 graduate of the Joint Advanced Warfighting School at National Defense University. His thesis examined Alfred Thayer Mahan’s theory of sea power and the strategic implications of the U.S. Merchant Marine’s decline. He has commanded the USS Monsoon (PC 4) in Bahrain and is currently the executive officer for the Naval Talent Acquisition Group Empire State in New York.
The opinions and views expressed here belong solely to the author and do not necessarily reflect those of the Department of Defense or the Department of the Navy, or their components. Any mention of commercial products or services does not imply Department of Defense endorsement. Additionally, the presence of external hyperlinks does not signify Department of Defense approval of the linked websites of their content, products, or services.
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