Can South Korean 105-Millimeter Ammunition Rescue Ukraine?

May 20, 2024: This commentary has been updated with revised ammunition statistics and information regarding South Korean government policy.

Artillery battles rage along the frontlines of the Russia-Ukraine war, with artillery causing about 80 percent of casualties. Ukraine urgently needs an influx of artillery ammunition to maintain its positions—let alone launch another counteroffensive to drive the Russians off Ukrainian territory. Last year, the Biden administration worked with South Korea's Yoon administration to send over 300,000 155-millimeter (mm) shells to Ukraine. The administration may need to re-tap the South Korean munitions stockpile to arm Ukraine in the face of dwindling stockpiles and congressional inertia. The good news is that South Korea may be willing to cooperate. 

Ukraine's Need for Artillery

Ukrainian officials say just holding the line requires 75,000 artillery shells a month, while another major offensive would require more than double that amount. In contrast, Russia fires around 300,000 each month and can sustain that with monthly production of about 250,000 and imports from North Korea.

To date, the United States has committed more than 3 million artillery shells of different calibers. The $300 million military aid package announced on March 12 will provide a short-term resupply of ammunition and other military equipment. The $60 billion supplemental Ukraine funding being debated in Congress would sustain Ukrainian resistance for many months. It would also help the United States increase monthly shell production to 100,000 by the end of 2025—up from the current monthly output of around 30,000—which will supply Ukraine's needs and sustain U.S. global war reserves.

The injection of new funding is vital for Ukrainian resistance but still leaves an ammunition gap because it will take months for production to ramp up.

Calling Seoul Again

South Korea has stepped up before. Press reports in April 2023 suggested that South Korea agreed to lend 300,000 155 mm artillery shells to the United States, likely with the understanding that the ammunition would allow the United States to replenish its stocks and send more ammunition to Ukraine. While the details of the agreement remain unknown, the United States may eventually replace the munitions, for example, by purchasing new munitions from South Korean producers.

Ammunition Production and the South Korean Industrial Base

The South Korean defense industry has become a major player in the global arms market and can now produce large amounts of ammunition. This industrial base expansion began in the late 1970s as South Korea capitalized on its commercial engineering expertise to produce basic weapons such as the KH178 105 mm towed howitzer. Since then, South Korea has developed cutting-edge weaponry like fourth-generation tanks, 4.5 generation fighters, and self-propelled howitzers—increasingly sought after by a growing number of countries, including NATO members. Poland, for example, recently signed a $2.6 billion deal to buy South Korean howitzers. 

The transferred munitions were reportedly once part of the Reserve Stockpile for Allies–Korea (WRSA-K), a forward-based U.S. conventional arms depot program terminated in the early 2000s. Following congressional authorization, the United States sold South Korea 155 mm munitions, explosives, and other arms as part of WRSA-K. South Korea had since maintained the WRSA-K munitions until the 2023 agreement with the United States.

However, South Korea likely cannot spare any more 155 mm shells without risking shortages in its own fight for survival. Like Ukraine, South Korea confronts a threatening and hostile neighbor while armed with a limited munitions stockpile and constrained production capacity. Indeed, some publicly available reports suggest South Korea could face munitions shortages within a week of a conventional conflict with North Korea.

Estimates put South Korea's annual production rate at around 200,000 155 mm shells per year. Ukraine’s armed forces, about the same size as South Korea's, fire that many projectiles in a month of heavy fighting.

105 mm Munitions in the K-Stockpile

What South Korea may be able to spare are 105 mm shells.

These 105 mm shells (around 33 pounds each) have less range and explosive power than 155 mm shells (around 95 pounds each), but the howitzers are lighter and more mobile. As Western 155 mm artillery stockpiles dwindle, the United States and others (United Kingdom, New Zealand, Italy, and Latvia) have provided Ukraine with 105 mm howitzers and ammunition. The Ukrainian army now operates an assortment of around 100 105 mm artillery pieces, including the U.S. M101, the U.S./UK M118/M119, and the Italian OTO Melara.

During the Vietnam War, these lighter howitzers proved indispensable in firebases, given their high mobility by road and air. Their light weight and mobility would allow Ukrainian artillery units to relocate quickly after firing, a crucial tactic for survivability on the modern battlefield. These howitzers would also allow Ukrainian battlefield commanders to conduct attacks on rough terrain against high-value targets. Rapid movement by helicopter could quickly reinforce threatened areas.

Public reports suggest South Korea has around 3.4 million 105 mm artillery shells, most which were once part of WRSA-K. These munitions would be compatible with all the 105 mm howitzers Ukraine operates.

Lending these munitions likely will not hurt South Korean military readiness. Less than 30 percent of howitzers operated by the South Korean military shoot 105 mm ammunition and the South Korean military is transitioning most units to 155 mm self-propelled howitzers like the domestically produced K9 Thunder.

The South Korean Ministry of Defense originally planned to decommission all 105 mm howitzers by 2020. Instead, to leverage the remaining 105 mm ammunition in the stockpile, it developed the K105 mobile howitzer by loading a refurbished towed 105 mm howitzer onto a five-ton truck. Around 200 are in operation today, assigned to support units that do not receive 155 mm self-propelled artillery. Ultimately, the South Korean military plans to transfer the K105 howitzers to reserve units.

A U.S. proposal to use the bulk of South Korea's 105 mm munitions stockpile, followed by replacing them with the currently in-production 155 mm ammunition, could appeal to South Korea.

A Politically and Militarily Advantageous Swap

The Yoon administration has a policy of only providing non-lethal aid. However, it has expressed a willingness to consider transferring lethal aid to Ukraine in the event of large-scale attacks on Ukrainian civilians.

There is an irony to note here. With South Korea helping the United States provide ammunition to Ukraine and North Korea providing ammunition to Russia, the two Koreas are, in effect, having a proxy war 4,500 miles from the peninsula.

Although upcoming midterm elections in South Korea create a politically delicate environment, the South Korean public broadly sympathizes with Ukraine. Yoon’s visit to Ukraine in July 2023 generally received high marks, and supporters of the Yoon administration cite foreign policy as a key factor driving Yoon’s strong job performance. The Yoon government thus might support a swap agreement for the 105 mm ammunition.

A swap agreement also enhances Korea's defense industrial partnership with the United States, which receives broad bipartisan support in South Korea. The Yoon government is pursuing the Reciprocal Defense Procurement Agreement, a procurement pact allowing easier access to each other's defense markets. Another munitions loan agreement—while not directly tied to ongoing negotiations over the procurement pact—would further the U.S.-South Korea bilateral industrial base partnership sought by South Korea.

Field artillery remains a cornerstone of battlefield lethality and combined arms. Indeed, as in earlier wars, artillery does most of the killing in this war. In the next phase of the war, a steady supply of artillery munitions—in tandem with other types of Western military assistance—will be crucial for the Ukrainian army to defeat Russian attacks and regain the offensive. An influx of South Korean 105 mm shells would enhance Ukrainian firepower and bridge a gap until U.S. aid is resumed.

Mark Cancian (Colonel, USMCR, ret.) is a senior adviser with the International Security Program at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Chris H. Park is a research assistant and program coordinator for the Arleigh A. Burke Chair at CSIS. 

Eric Williams, a U.S. Marine Corps military fellow at CSIS, contributed to this commentary.

Chris Park
Program Coordinator and Research Assistant, Arleigh A. Burke Chair in Strategy