New Delhi, Aug. 18 -- Anastasiia Holubieva was reaching back to scratch her head when she felt the blood. Shrapnel from the missile attack on Kyiv on Sunday had caught her in the back before she even knew it had landed, before the dust had settled on one more night when the air defense system that was supposed to stop it barely tried.

Ukraine has run so short of interceptors that its operators are making triage decisions about which missiles are worth shooting at, saving what little ammunition remains for threats to the most critical targets.

The United States is running low too. The Iran war consumed more than 800 Patriot PAC-3 MSE interceptors in its opening days alone, according to RFE/RL, drawing down a stockpile that had stood abov...