“200 miles of ocean you own — until someone decides you don’t.” The exploitation gap between international maritime law and enforcement reality.
Executive Summary
Under UNCLOS (the UN Convention on the Law of the Sea), a coastal state holds an Exclusive Economic Zone extending 200 nautical miles from its baseline, granting it sovereign rights over all fisheries, hydrocarbons, and seabed resources within that zone. EEZ Encroachment occurs when another state conducts fishing, resource extraction, military surveillance, or territorial assertion within that zone without consent — a pattern that has escalated dramatically in the South China Sea, East China Sea, and Arctic since 2020. The critical vulnerability: UNCLOS grants rights but provides no enforcement mechanism beyond diplomatic protest and international arbitration, which non-compliant states simply ignore.
The Strategic Mechanism
Encroachment operates on three escalating levels:
Level 1 — Resource Extraction:
- Illegal, unreported, and unregulated (IUU) fishing by state-backed fleets within another state’s EEZ
- Unilateral hydrocarbon exploration and drilling in disputed overlapping EEZ claims
Level 2 — Presence Assertion:
- Coast guard and maritime militia vessels conducting “law enforcement” patrols within another state’s EEZ
- Construction of artificial islands or structures within contested EEZ areas (China’s island-building in the Spratlys)
Level 3 — Access Denial:
- Physically blocking foreign vessels from reaching their own EEZ resources (water cannons, ramming, laser dazzling)
- Military exercises within another state’s EEZ intended to signal capability to permanently deny access
Market & Policy Impact
- Energy investment freeze: Oil majors including Shell and TotalEnergies have deferred South China Sea exploration blocks due to encroachment risk and unresolvable title uncertainty
- Fisheries collapse risk: IUU fishing in encroached EEZs is depleting fish stocks on which developing nations’ food security and export revenues depend
- Insurance market: Political violence and expropriation insurance premiums for offshore energy assets in disputed EEZ areas have surged 30–50% since 2022
- Alliance credibility: Every U.S. statement on EEZ defense obligations is parsed by Beijing, Manila, Hanoi, and Tokyo as a test of deterrence
- Arbitration irrelevance: China’s rejection of the 2016 Permanent Court of Arbitration ruling — which found its South China Sea claims unlawful — has set a precedent for ignoring adverse UNCLOS rulings
Modern Case Study: Philippines vs. China at Reed Bank, 2024
Reed Bank (Recto Bank), located squarely within the Philippines’ UNCLOS-defined EEZ, holds an estimated 5.4 trillion cubic feet of natural gas. In 2024, a Philippine company’s planned drilling program at the site was systematically obstructed by Chinese coast guard vessels and maritime militia. Filipino Defense Secretary Teodoro stated publicly: “We are not intruding into another country’s EEZ — the encroacher occupies a vast expanse of sea.” Washington affirmed that the Mutual Defense Treaty covered Philippine vessels and aircraft in the area. Beijing continued to classify its actions as domestic law enforcement within what it calls Chinese territorial waters — a claim with no standing under international law but with significant practical effect. The energy trapped under Reed Bank remained inaccessible, illustrating how EEZ encroachment can function as an effective resource-denial strategy regardless of legal merits.