Policy Implications

Why global security coordination is a public good — and why we’re free-riding

The Collective Action Problem

The findings point to an uncomfortable possibility: peace near strategic waterways may be partly a byproduct of self-interest, not coordinated policy.

When trade is booming, major powers protect choke points because it serves their economic interests. But this protection is unreliable — it depends on trade volumes and the self-interest calculus of a few powerful nations.

WarningThe Free-Rider Problem

As economist Mancur Olson showed in his classic 1965 work, public goods — benefits everyone shares but nobody individually pays for — tend to be underprovided. Global maritime security is a textbook case: every nation benefits from open shipping lanes, but intervention is costly and risky.

What This Means for Policy

The research points toward three implications:

1. Supranational coordination matters. Relying on major powers’ self-interest is insufficient. Organizations like the United Nations should play a larger role in guaranteeing safe maritime passage — especially during periods of low trade.

2. Trade agreements are security agreements. The estimates suggest that higher trade openness is associated with less conflict in strategic locations. Trade policy and security policy are more intertwined than commonly assumed.

3. Deglobalization carries security risks. If world trade openness declines — as some current trends suggest — the protective effect weakens, and strategic locations become more contested again.

Through the Lens of 2026

The paper’s data ends in 2018. But its framework is more relevant than ever.

Tariffs and the Return to the “Conflict Zone”

The post-2018 world has moved sharply toward deglobalization. In 2025, the United States imposed sweeping tariffs — a 145% tariff on Chinese goods, a 25% tariff on imports from Canada and Mexico, and a baseline 10% tariff on most other countries. The WTO’s Global Trade Outlook (April 2025) projects global merchandise trade volumes will decline by 0.2% in 2025, with North American trade growth dropping by 1.7 percentage points.

The paper’s framework suggests that falling trade openness would push the world back below the 0.534 tipping point, into the zone where proximity to choke points is associated with more violence. If the current tariff escalation depresses global trade, the estimated protective effect weakens — and strategic locations may become more vulnerable.

The Red Sea Crisis: Bab el-Mandeb Under Fire

Since November 2023, Houthi forces in Yemen have launched over 190 attacks on commercial shipping transiting the Bab el-Mandeb strait — one of the 12 choke points in our analysis. Traffic through the Suez Canal dropped by roughly 75%, forcing vessels to reroute around the Cape of Good Hope at an additional cost of approximately $1 million in fuel per voyage and 11,000 extra nautical miles. The UNCTAD Global Trade Update (January 2026) estimates over $1 trillion in goods were disrupted.

WarningA Test of the Framework

The Houthi crisis both confirms and challenges the model. On one hand, it confirms the paper’s core insight: conflict erupts at a strategically vital waterway, exactly as the framework predicts. On the other hand, major powers did intervene — the US-led Operation Prosperity Guardian and the EU’s EUNAVFOR Aspides — yet attacks persisted. This illustrates an important nuance: the model predicts incentives to intervene when trade stakes are high, not guaranteed success. The collective action problem is real: intervention is costly and difficult to sustain.

Strait of Hormuz: A Live Flashpoint

In February 2026, Iran conducted live fire naval drills and briefly closed the Strait of Hormuz on February 17, while joint Iran-Russia naval exercises took place at the port of Bandar Abbas. An estimated 20–30% of the world’s daily oil consumption transits through Hormuz. The United States responded by boosting its naval presence in the region — consistent with the Montesquieu mechanism: high trade stakes are associated with major power intervention to keep the route open.

This is the same dynamic illustrated by the France-Netherlands EMASOH (European Maritime Awareness in the Strait of Hormuz) mission, which has maintained frigate patrols since 2020. But rising US-Iran tensions also show that strategic territory remains a flashpoint, regardless of intervention.

What the Model Predicts Next

If tariffs and deglobalization continue to depress world trade openness, the framework predicts a dangerous trajectory: a slide further below the tipping point, where the marginal effect of proximity turns positive and choke points become conflict magnets. The chart below shows historical trade openness — readers can judge for themselves how close we are to the edge.

World Trade Openness Over Time

tradeData = FileAttachment("data/trade_openness.json").json()

{
  const width = 700;
  const height = 350;
  const margin = {top: 30, right: 30, bottom: 50, left: 60};

  const crossover = 0.534;

  const x = d3.scaleLinear()
    .domain(d3.extent(tradeData, d => d.year))
    .range([margin.left, width - margin.right]);

  const yExtent = d3.extent(tradeData, d => d.trade_openness);
  const y = d3.scaleLinear()
    .domain([Math.min(yExtent[0], 0.34), Math.max(yExtent[1], 0.62)])
    .range([height - margin.bottom, margin.top]);

  const svg = d3.create("svg")
    .attr("viewBox", [0, 0, width, height])
    .attr("width", width)
    .attr("height", height)
    .style("max-width", "100%")
    .style("font-family", "'Source Sans 3', sans-serif");

  // Danger zone (below crossover)
  svg.append("rect")
    .attr("x", margin.left).attr("y", y(crossover))
    .attr("width", width - margin.left - margin.right)
    .attr("height", y(0.34) - y(crossover))
    .attr("fill", "#ffebee").attr("opacity", 0.5);

  // Safe zone (above crossover)
  svg.append("rect")
    .attr("x", margin.left).attr("y", y(0.62))
    .attr("width", width - margin.left - margin.right)
    .attr("height", y(crossover) - y(0.62))
    .attr("fill", "#e8f5e9").attr("opacity", 0.5);

  // Zone labels
  svg.append("text")
    .attr("x", width - margin.right - 5).attr("y", y(crossover) + 15)
    .attr("text-anchor", "end").attr("fill", "#c62828")
    .attr("font-size", "10px").attr("font-weight", "600")
    .text("CONFLICT ZONE");

  svg.append("text")
    .attr("x", width - margin.right - 5).attr("y", y(crossover) - 6)
    .attr("text-anchor", "end").attr("fill", "#2e7d32")
    .attr("font-size", "10px").attr("font-weight", "600")
    .text("PEACE ZONE");

  // Crossover line
  svg.append("line")
    .attr("x1", margin.left).attr("x2", width - margin.right)
    .attr("y1", y(crossover)).attr("y2", y(crossover))
    .attr("stroke", "#7e57c2").attr("stroke-dasharray", "6,3").attr("stroke-width", 1.5);

  svg.append("text")
    .attr("x", margin.left + 5).attr("y", y(crossover) - 6)
    .attr("fill", "#7e57c2").attr("font-size", "10px")
    .text(`Tipping point: ${crossover}`);

  // Trade openness line
  const line = d3.line()
    .x(d => x(d.year))
    .y(d => y(d.trade_openness))
    .curve(d3.curveMonotoneX);

  svg.append("path")
    .datum(tradeData)
    .attr("d", line)
    .attr("fill", "none")
    .attr("stroke", "#1a237e")
    .attr("stroke-width", 2.5);

  // Data points
  svg.append("g")
    .selectAll("circle")
    .data(tradeData)
    .join("circle")
    .attr("cx", d => x(d.year))
    .attr("cy", d => y(d.trade_openness))
    .attr("r", 3)
    .attr("fill", d => d.trade_openness >= crossover ? "#43a047" : "#e53935");

  // Annotations for key events
  const annotations = [
    {year: 1991, label: "End of Cold War", dy: -15},
    {year: 2001, label: "China joins WTO", dy: 20},
    {year: 2008, label: "Financial crisis", dy: -15},
  ];

  for (const a of annotations) {
    const datum = tradeData.find(d => d.year === a.year);
    if (datum) {
      svg.append("line")
        .attr("x1", x(a.year)).attr("x2", x(a.year))
        .attr("y1", y(datum.trade_openness) + (a.dy > 0 ? 6 : -6))
        .attr("y2", y(datum.trade_openness) + a.dy)
        .attr("stroke", "#999").attr("stroke-width", 1);

      svg.append("text")
        .attr("x", x(a.year)).attr("y", y(datum.trade_openness) + a.dy + (a.dy > 0 ? 12 : -4))
        .attr("text-anchor", "middle").attr("fill", "#666")
        .attr("font-size", "9px").attr("font-weight", "600")
        .text(a.label);
    }
  }

  // Axes
  svg.append("g")
    .attr("transform", `translate(0,${height - margin.bottom})`)
    .call(d3.axisBottom(x).ticks(8).tickFormat(d3.format("d")))
    .call(g => g.append("text")
      .attr("x", width / 2).attr("y", 40)
      .attr("fill", "#555").attr("text-anchor", "middle")
      .attr("font-size", "13px")
      .text("Year"));

  svg.append("g")
    .attr("transform", `translate(${margin.left},0)`)
    .call(d3.axisLeft(y).ticks(6).tickFormat(d3.format(".2f")))
    .call(g => g.append("text")
      .attr("transform", "rotate(-90)")
      .attr("x", -height / 2).attr("y", -45)
      .attr("fill", "#555").attr("text-anchor", "middle")
      .attr("font-size", "13px")
      .text("World Trade Openness (share of GDP)"));

  return svg.node();
}

TipReading the chart

Each dot represents one year of global trade openness. When trade is above the tipping point (0.534), the conflict premium near choke points disappears — proximity is no longer associated with higher violence. When trade drops below, locations near choke points are associated with disproportionately more conflict. Notice how the 2008 financial crisis pushed trade back toward the danger zone.

Learn more about the authors, cite the paper, or access the replication data. Next: About