WASHINGTON — The Pentagon is tapping into a vast but little-known stockpile of American ammunition in Israel to help meet Ukraine’s dire need for artillery shells in the war with Russia, American and Israeli officials say.
The stockpile provides arms and ammunition for the Pentagon to use in Middle East conflicts. The United States has also allowed Israel to access the supplies in emergencies.
The Ukraine conflict has become an artillery-driven war of attrition, with each side lobbing thousands of shells every day. Ukraine has run low on munitions for its Soviet-era weaponry and has largely shifted to firing artillery and rounds donated by the United States and other Western allies.
Artillery constitutes the backbone of ground combat firepower for both Ukraine and Russia, and the war’s outcome may hinge on which side runs out of ammunition first, military analysts say. With stockpiles in the United States strained and American arms makers not yet able to keep up with the pace of Ukraine’s battlefield operations, the Pentagon has turned to two alternative supplies of shells to bridge the gap: one in South Korea and the one in Israel, whose use in the Ukraine war has not been previously reported.
The shipment of hundreds of thousands of artillery shells from the two stockpiles to help sustain Ukraine’s war effort is a story about the limits of America’s industrial base and the diplomatic sensitivities of two vital U.S. allies that have publicly committed not to send lethal military aid to Ukraine.
Israel has consistently refused to supply weapons to Ukraine out of fear of damaging relations with Moscow and initially expressed concerns about appearing complicit in arming Ukraine if the Pentagon drew its munitions from the stockpile. About half of the 300,000 rounds destined for Ukraine have already been shipped to Europe and will eventually be delivered through Poland, Israeli and American officials said.
As senior defense and military officials from dozens of nations, including NATO states, prepare to meet at Ramstein Air Base in Germany on Friday to discuss sending Ukraine more tanks and other arms, U.S. officials have been scrambling behind the scenes to cobble together enough shells to keep Kyiv sufficiently supplied this year, including through an anticipated spring offensive.
“With the front line now mostly stationary, artillery has become the most important combat arm,” Mark F. Cancian, a former White House weapons strategist, said in a new study for the Center for Strategic and International Studies in Washington, where he is a senior adviser.
Another analysis published last month by the Foreign Policy Research Institute said that if Ukraine continued to receive a steady supply of ammunition, particularly for artillery, as well as spare parts, it would stand a good chance of wresting back more territory that Russia had seized.
“The question is whether these advantages will prove sufficient for Ukrainian forces to retake territory from entrenched Russian troops,” wrote Rob Lee and Michael Kofman, leading military analysts.
Arming the Ukrainian military with enough artillery ammunition is part of a larger American-led effort to increase its overall combat power by also providing more precision long-range weapons, Western tanks and armored fighting vehicles, and combined arms training.
The United States has so far sent or pledged to send Ukraine just over one million 155-millimeter shells. A sizable portion of that — though less than half — has come from the stockpiles in Israel and South Korea, a senior U.S. official said, speaking on the condition of anonymity to discuss operational matters.
Other Western countries, including Germany, Canada, Estonia and Italy, have sent 155-millimeter shells to Ukraine.
The Ukrainian army uses about 90,000 artillery rounds a month, about twice the rate they are being manufactured by the United States and European countries combined, U.S. and Western officials say. The rest must come from other sources, including existing stockpiles or commercial sales.
Mr. Kofman said in an interview that without adjustments to how the Ukrainian military fights, future Ukrainian offensives might require significantly more artillery ammunition to make progress against entrenched Russian defenses.
“The U.S. is making up the difference from its stockpiles, but that’s doubtfully a sustainable solution,” said Mr. Kofman, who is the director of Russian studies at CNA, a research institute in Arlington, Va. “It means the U.S. is taking on risk elsewhere.”
Pentagon officials say they must ensure that even as they arm Ukraine, American stockpiles do not dip to dangerously low levels. According to two senior Israeli officials, the United States has promised Israel that it will replenish what it takes from the warehouses in its territory and would immediately ship ammunition in a severe emergency.
“We are confident that we will continue to be able to support Ukraine for as long as it takes,” Brig. Gen. Patrick Ryder, the Pentagon spokesman, told reporters last week. “And we’re confident that we’ll be able to continue to maintain the readiness levels that are vital to defending our nation.”
General Ryder told The New York Times in a statement on Tuesday that the Pentagon “will not discuss the location or units providing the equipment or materiel,” citing operational security reasons.
What we consider before using anonymous sources. Do the sources know the information? What’s their motivation for telling us? Have they proved reliable in the past? Can we corroborate the information? Even with these questions satisfied, The Times uses anonymous sources as a last resort. The reporter and at least one editor know the identity of the source.
And those war reserve stockpiles are playing a pivotal role.
When last year the Pentagon first raised the idea of withdrawing munitions from the stockpile, Israeli officials expressed concern about Moscow’s reaction.
Israel has imposed a near-total embargo on selling weapons to Ukraine, fearing that Russia might retaliate by using its forces in Syria to limit Israeli airstrikes aimed at Iranian and Hezbollah forces there.
Israel’s relationship with Russia has come under close scrutiny since Russia’s invasion of Ukraine last February, and Ukrainian officials have called out Israel’s government for offering their country only limited support and bowing to Russian pressure.
As the war dragged on, the Pentagon and the Israelis reached an agreement to move about 300,000 155-millimeter shells, Israeli and American officials said.
The American desire to move the munitions was officially submitted in an encrypted phone conversation between the U.S. secretary of defense, Lloyd J. Austin III, and Benny Gantz, the Israeli minister of defense at the time, according to an Israeli official who was briefed on the details of the conversation.
Mr. Gantz brought the issue to the Israeli cabinet. The officials asked to hear the opinion of the defense establishment, whose representatives recommended accepting the plan to avoid tension with the United States, in part because the ammunition was American property. Yair Lapid, then the prime minister, approved the request at the end of the discussion.
The Israeli officials said that Israel had not changed its policy of not providing Ukraine with lethal weapons and rather was acceding to an American decision to use its own ammunition as it saw fit.
“Based on a U.S. request, certain equipment was transferred to the U.S. D.O.D. from its stockpiles” in Israel, a spokesman for the Israeli Defense Forces said in a statement, referring to the Department of Defense.
The stockpile of American military hardware and munitions in Israel has its origins in the 1973 Arab-Israeli War, which saw the United States airlifting weapons to resupply Israeli forces.
After the war, the United States established warehouses in Israel so that it could rely on them if it were again caught in a crisis. A strategic memorandum signed by the two countries in the 1980s paved the way for the “pre-positioning” of Pentagon assets in Israel, according to two former U.S. officials and a former senior Israeli military officer with direct knowledge of the agreement.
American tanks and armored personnel carriers were initially moved to Israel’s southern desert with the understanding that they would be used by U.S. forces in the region if needed, said the officials, who spoke on the condition of anonymity to discuss sensitive internal deliberations.
In the 2000s, the program was expanded to include munitions for the U.S. Army, Navy and Air Force — all stored in separate locations accessible only to American military personnel, according to a former U.S. arms inspector.
At the time, the stockpile, officially called the WRSA-I, or War Reserve Stocks for Allies-Israel, was overseen by the U.S. European Command. But it is now managed by the U.S. Central Command, following a redrawing of its area of responsibility in September 2021.
Israel was allowed to withdraw American munitions from the stockpile during its war with Hezbollah in the summer of 2006 and again during operations against Hamas in the Gaza Strip in 2014, according to a Congressional Research Service report released in February 2022.
The Pentagon also approached South Korea last year about transferring munitions in the U.S. stockpile there to Ukraine.
The South Koreans were more willing than the Israelis to work with the United States on using the stocks, a senior U.S. official said. But they also objected to shipping artillery shells directly to Ukraine, though for different reasons, the official said. The South Korean government did not want artillery rounds marked R.O.K. (Republic of Korea) showing up in Ukraine in violation of South Korean arms export rules.
A compromise was reached. Artillery shells from the Korean stockpile would be sent to replenish American stocks elsewhere.
The United States has also agreed to buy 100,000 new artillery shells from South Korea, a deal previously reported by The Wall Street Journal.
U.S. officials say that accessing the overseas stocks will help tide over the Ukrainians until American ammunition makers can ramp up their production.
Other factors may ease the pressure for more shells. Russia’s artillery fire has reduced sharply in recent weeks, Pentagon officials said, possibly reflecting rationing of rounds because of low supplies. White House officials said in November that North Korea was shipping artillery shells to Russia, another sign of likely munitions shortages, U.S. officials said.
Finally, the United States is helping Ukraine use ammunition more efficiently. The Ukrainians have been firing so many artillery barrages that about a third of the 155-millimeter howitzers provided by the United States and other Western nations are out of commission for repairs.
Over the summer, during intense fighting between Ukraine and Russia in the eastern region of Donbas, Pentagon officials gathered satellite imagery that showed the devastation wrought on farmland between the two forces’ trench lines. Fields had been transformed into moonscapes, pitted and pocked with thousands of crater shells.
Since then, American officials have leaned on Ukrainians to use their artillery more judiciously. And the arrival of precision rocket artillery, like HIMARS rocket artillery, has allowed Ukraine to strike more expertly.
Eric Schmitt, Adam Entous, John Ismay and Thomas Gibbons-Neff reported from Washington. Ronen Bergman reported from Tel Aviv. Julian E. Barnes in Washington, Choe Sang-Hun in Seoul and Lara Jakes in Rome contributed reporting.