Initially, Israeli officials expressed fear that the decision could harm relations with Russia.
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.
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.
