From the article:

The United States launched more than 200 Terminal High Altitude Area Defense, or THAAD, interceptors in defense of Israel — roughly half of the Pentagon’s total inventory — along with more than 100 Standard Missile-3 and Standard Missile-6 interceptors fired from naval vessels in the eastern Mediterranean, said the U.S. officials, who, like others in this article, spoke on the condition of anonymity to discuss sensitive security matters. By contrast, Israel fired fewer than 100 of its Arrow interceptors and around 90 David’s Sling interceptors, some of which were used against less sophisticated projectiles fired by Iran-backed groups in Yemen and Lebanon.

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The shortage of U.S. interceptors has alarmed U.S. allies in Asia, particularly Japan and South Korea, which rely on the United States as a deterrent to potential threats from North Korea and China. “That bill risks coming due in theaters that have nothing to do with Iran,” said Grieco.

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“Israel is not capable of fighting and winning wars on its own, but nobody actually knows this, because they never see the back end,” said a second administration official.

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Israel relies more heavily on lower-tier systems such as Iron Dome and David’s Sling to counter projectiles from groups such as Hezbollah and the Houthis, while conserving its more sophisticated interceptors. The result, officials said, was a “significant” drawdown of U.S. stockpiles while Israel was able to maintain its higher-end air defense stockpiles.