Interdicting North Korean Vessels: Another False Hope

(Photo: US Navy/Petty Officer 2nd Class Nathan Serpico)

Keeping maritime pressure on North Korea to prevent illicit trade will continue to be one tool the international community can wield against threatening North Korean behavior, but it will not force Pyongyang’s hand.[1] In response to North Korea’s sixth nuclear test on September 3, the US sought authorization in UN Security Council Resolution (UNSCR) 2375 to obtain the international legal authority for states to use military force on the high seas, if necessary, to stop, board and seize ships of the North Korean merchant fleet and its trading partners, if they were thought to be engaged in sanctions violations. Due to Russian and Chinese opposition, that authorization was stripped out from the US draft, although the final resolution will incrementally tighten the noose around North Korea’s use of seaborne trade to sustain its economy and supply its nuclear and missile programs.[2] But even if Washington obtains Security Council authorization for use of force on the high seas in the future, it might not use it and such interdictions would be unlikely to prove decisive.

A History of US Maritime Interdiction Operations

Over the past 15 years, the US has led the international community in setting new norms and policies on interdicting maritime traffic in the fight against weapons of mass destruction (WMD) and missile proliferation. Since the end of the Cold War, Washington has also increasingly used its sea power and diplomatic clout to enforce UN sanctions in the maritime domain. In fact, some argue that North Korea was the catalyst for the US enhancing maritime interdiction as a tool of national security policy.

The event that focused US attention was the interdiction of the merchant vessel (M/V) So San in 2002. The vessel, tracked by US Navy ships and aircraft, was stopped and boarded on the high seas by Spanish Navy forces cooperating with Washington. The North Korean crew attempted to resist the boarding, and the legal basis for the Spanish boarding was contested with Washington and Madrid, arguing that when the crew hauled down its flag it became a stateless vessel. A search of the cargo discovered Scud missiles, a certainly dangerous shipment but not illegal at the time. The Yemeni government eventually admitted that it was the intended recipient, and Washington—after securing pledges that Yemen would not re-transfer the missiles—allowed the shipment to go through.[3] It was not clear that there would have been a legal basis for seizing the shipment.

In part, because of the gaps in legal authority exposed by the So San incident, Washington worked with like-minded states to create a more robust approach to interdiction of WMD and missile-related goods. The result was the Proliferation Security Initiative (PSI) followed by the 2005 Protocol to the Convention for the Suppression of Unlawful Acts Against the Safety of Maritime Navigation, which provided an international legal basis for outlawing maritime transportation of WMD components.[4] Among the slew of United Nations Security Council resolutions against North Korea since 2006, almost all contained provisions related to maritime transportation and interdiction.

Beginning with UNSCR 1718 in 2006, the provisions became progressively stricter with the goal of cutting off North Korea’s ability to use ships to import materials that contributed to its conventional and unconventional military capabilities or export goods that brought it revenues that supported the regime. The resolutions authorized states, consistent with national and international law, to interdict and inspect ships going to and from North Korea if there was reasonable suspicion that the vessels were violating UN sanctions. The Security Council also decided that states were to ban use of their registry (flagging) for ships of the DPRK and to deny DPRK-flagged ships use of fueling and other port services. Resolutions also attempted to shame states into compliance, allowing states to report to the UN sanctions committee the registry of ships that refused inspection requests on the high seas. Finally, vessels identified by the sanctions committee as violators were to be denied entry into ports, discouraging cooperation with the DPRK.

Two events over this time period, one an actual interdiction and seizure of contraband and the other a corralling of a North Korean vessel, illustrate the tightening noose of maritime constraints as well as ongoing limitations. In 2011, the US Navy shadowed a North Korean-crewed, Belize-flagged merchant vessel with a suspected cargo of missiles, the M/V Light, from North Korea toward Myanmar. The US had a boarding agreement with Belize, which allowed the US to ask for permission to board the vessel and inspect it on the high seas.[5] Despite Belize’s permission, the North Korean crew refused multiple boarding requests. Fearing potential escalation or a trap to embarrass Washington with an empty cargo hold, the US chose not to attempt an opposed boarding. Washington pressured Myanmar diplomatically, and the M/V Light returned to North Korea without pulling into Myanmar.[6]

In 2013, Panamanian officials stopped and inspected the Chon Chong Gang, a North Korean-flagged and crewed vessel passing through the Panama Canal. Panamanian marines overwhelmed resistance by the North Korean crew. Underneath sugar in the ship’s hold were a range of older conventional weapons and parts that were heading to North Korea for refurbishment and upgrading. The Cuban government brushed it off as old weapons and claimed that conventional weapons repairs were not covered by the various UNSCRs against North Korea.[7] Those seeking to enforce sanctions against North Korea had gotten lucky in this interdiction through a combination of good intelligence, a willing state guarding a chokepoint, and a North Korean ship that likely did not have the range to sail around South America without stopping for fuel and thereby risking inspection and seizure. The haul, however, was minor.

Back to the Future?

North Korea, desperate for hard currency and parts to support its conventional and unconventional arsenals, has adjusted to the sanctions and maritime interdiction efforts. As states have deregistered vessels owned by North Korea, there has been an increase in the number of vessels registered in North Korea. Pyongyang has changed some of its ships to its “domestic fleet”—thereby evading the UNSCRs and possibly allowing the vessels to sail without certain identifying data being broadcast.[8] North Korea will continue to risk its ships being stopped or seized.

However, the UNSCRs and state actions to comply with them in the areas of maritime shipment and interdiction are reducing the scale and scope of North Korea’s maritime operations. Its fleet is dwindling as states no longer sell vessels or allow them to register. Ports and even fueling services are denied and are also dangerous as ships can easily be boarded, inspected and seized in such circumstances. So what is left to North Korea now is mostly a smaller, older, less-capable fleet that needs to sail directly to states willing to risk trade with Pyongyang. The rusting freighter Jie Shun, pulled into port in August and was inspected by Egypt after the US shamed Cairo into it is but the latest example.[9]

It is not likely that North Korea would have changed its behavior even if the US-proposed language on maritime interdiction were granted in UNSCR 2375. At best, the threat of high seas boarding might have frightened away some of the last states willing to look the other way and allow the DPRK to register their vessels. The concern that the US had when considering whether to board the M/V Light on the high seas—military escalation by North Korea—is likely the reason that Beijing and Moscow opposed that provision in the most recent resolution.

Even with authorization, Washington would face the same question if it caught a North Korean vessel on the high seas. It would have international legal blessing, but would the rewards justify the risks? What if the ship contained nothing of significance such as the Chon Chong Gang? In addition to the potential for violence and casualties during the boarding, how might North Korea react? Would it see such a maneuver as an act of war and escalate on the peninsula?

Almost as problematic for US policy, the threat of armed boarding might also ring hollow if the US could not regularly muster and assign the right types and numbers of forces to track and threaten boarding of North Korean vessels. After the recent accidents involving US warships in East Asia, Washington may be looking to reduce operations tempo rather than increase it in the region.[10] US ships in the region also have other high-priority missions ranging from ballistic missile defense to presence operations in the South and East China Seas. Moreover, even if the requisite ships and aircraft are available to trail North Korean-flagged and crewed merchant vessels, the US will need specialized teams to face what will likely be increasingly hostile opposition to boarding. An actively opposed visit, board, search and seizure (VBSS) operation of a high freeboard ship is typically an operation for US special operations forces that are already stretched thin.[11]


None of this means that maritime interdiction is not useful as one element of a broader strategy of coercive diplomacy against North Korea. The maritime elements of the UNSCRs and actions by cooperating states have reduced Pyongyang’s ability to generate revenues or import military capabilities using the seas. It remains an area where the US and its allies hold a tremendous advantage, and it should be continued to be leveraged as part of a broader strategy. But as it has done with all of the other sanctions that have been imposed on it, North Korea will find clever and effective ways, if necessary, to mitigate the impact of a tightening maritime interdiction noose.

  1. [1]

    The views are those of the author alone and do not represent the views or policies of the US Naval War College, the US Navy, or the US Department of Defense.

  2. [2]

    United Nations Security Council Resolution 2375, September 11, 2017.

  3. [3]

    David E. Sanger and Thom Shanker, “THREATS AND RESPONSES: WAR MATÉRIEL; Reluctant U.S. Gives Assent For Missiles to Go to Yemen,” The New York Times, December 12, 2002,

  4. [4]
  5. [5]

  6. [6]

    David E. Sanger, “U.S. Said to Turn Back North Korean Missile Shipment,” The New York Times, June 12, 2011,

  7. [7]

  8. [8]

    Midterm report of the Panel of Experts established pursuant to resolution 1874 (2009), S/2017/742, September 5, 2017,

  9. [9]
  10. [10]

    David B. Larter, “How the US Navy’s Fleet has been on a collision course for years,” DefenseNews, August 27, 2017,

  11. [11]

    Staff Sgt. Robert Storm, “MARSOC Conducts Maritime Operations Training,” New Article, July 11, 2013,

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