Naval buildup is a must for energy-dependent Korea

South Korea’s security does not end at the border with North Korea. Crude oil and liquefied natural gas from the Middle East must cross distant seas and reach our ports to keep factories running and sustain everyday life. Merchant ships carrying Korean exports also travel the world’s shipping routes. Sea lanes are the lifelines of our economy. With world-class shipbuilding capabilities and extensive international trade, have we also secured sufficient capacity to protect those lifelines?

South Korea’s defense posture has evolved primarily in response to the threat posed by North Korea’s ground forces. There were sound reasons for committing substantial resources to land defense, yet we must ask whether threats in distant waters and the importance of maritime security have received sufficient attention. Operational planning that places considerable weight on U.S. naval support has also contributed to an underestimation of the need for South Korea’s own oceangoing forces.

The South Korea-U.S. alliance remains central to our security, but combined operations to defend the peninsula and missions to protect sea lanes around the world differ in scope and circumstances. The U.S. deploys its forces according to its national interests and global strategy. When crises erupt simultaneously in several regions, Washington must decide where to first send ships and supporting forces. We cannot assume that protecting South Korea’s energy shipments and merchant vessels will always be its highest priority.

An independent capacity to protect sea lanes does not mean controlling every ocean alone. It means being able to identify threats, deploy forces where needed and protect the vessels essential to our people and economy. It also means having the capability to exercise our own judgment and shoulder our share of joint operations with allies and partners.

The South Korean Navy has accumulated experience in distant water operations through deployments of the Cheonghae Unit and overseas exercises. It would be inaccurate to suggest that it lacks oceangoing operational capabilities. The question is whether it has sufficient capacity to protect merchant shipping against high-intensity threats and sustain that mission over an extended period. Experience gained from peacetime overseas deployments does not automatically guarantee the ability to protect shipping routes in wartime.

Building naval power requires substantial funding and years of preparation. Designing and constructing ships must go hand in hand with training crews, securing maintenance facilities and establishing ammunition and logistics systems. In competition for funding to address immediate threats from North Korea, risks in distant waters can easily fall down the list of priorities. However, increasing the budget after a crisis erupts cannot instantly produce experienced crews or a fleet ready to deploy.

The prominence of countering infiltration by North Korean vessels and responding to coastal provocations in earlier naval missions has also shaped this outlook. These were essential duties, but they helped reinforce the perception that the Navy’s role was primarily coastal defense. The Navy must also consider whether it has adequately explained the importance of maritime security to the public. Before discussing the size and armament of warships, it should explain how safe sea lanes affect electricity bills, fuel prices and jobs.

The Strait of Hormuz illustrates that connection. The International Energy Agency identifies South Korea and Japan as countries particularly dependent on crude oil passing through the strait. Military clashes and attacks on merchant vessels in the region demonstrate that risks to energy transportation are more than hypothetical. Restrictions on passage can disrupt supplies, while reluctance to enter the area and higher war-risk insurance premiums can raise import costs even without a complete closure.

The impact extends far beyond prices at the pump. It puts pressure on feedstock supplies for refineries and petrochemical plants, as well as fuel supplies for power generation. Rising freight rates and production costs affect export competitiveness and consumer prices. Releasing strategic oil reserves and diversifying import sources are essential responses. But reserves are finite and alternative supplies cannot always be secured immediately. Ships departing from ports inside the Persian Gulf cannot avoid the Strait of Hormuz simply by choosing a different route.

Energy security must therefore encompass safe transportation, as well as purchasing and stockpiling. Deploying warships, however, cannot resolve every problem. Escorting merchant vessels and reopening a blockaded strait involve different risks and force requirements. Naval power becomes an effective instrument only when integrated with diplomacy, energy policy and measures to support commercial shipping.

On Feb. 1, 2025, the South Korean Navy established its Fleet Command, identifying the protection of sea lanes as one of its missions. This was a meaningful step forward. The next task is to turn the creation of an organization into a sustained operational capability. Operations far from home require a force centered on destroyers and logistics support ships, with submarines and aircraft integrated as the mission demands. They also require intelligence and communications systems, access to overseas ports and arrangements for resupply. What matters is not simply the number of ships in the inventory but the forces that can actually deploy and sustain their missions.

Even escorting merchant ships is difficult in waters threatened by a combination of mines, anti-ship missiles, submarines and drones. Air defense, anti-submarine warfare and mine countermeasures must work together, supported by regular training with partner navies. The government and shipping industry should establish priorities for vessels requiring protection, share threat information and prepare evacuation and rerouting procedures. Deployed forces need clearly defined missions, a sound legal basis and rules of engagement.

Naval force development cannot be measured solely against North Korea. South Korea must fulfill its responsibility to defend the peninsula while also protecting its people and economic activities overseas. Maintaining a permanent fleet presence in every ocean may be unrealistic, but we must be able to deploy the necessary forces to critical shipping routes in time. That requires consistent, long-term support for funding, skilled personnel, maintenance and logistics.

Naval power is not a product that can be ordered and delivered when a crisis strikes. Decisions made today will determine the options available to the country a decade or more from now. We can purchase energy abroad, but we cannot delegate to another country our responsibility to secure its safe transport. Building a navy commensurate with South Korea’s national capabilities and dependence on overseas trade is essential preparation for protecting everyday life and the national economy.

Retired Navy Capt. Moon Keun-sik is an adjunct professor at the Graduate School of Public Policy at Hanyang University in Seoul.