The war in Iran has exacerbated a shortage of missile-defense weaponry that is likely to plague the U.S. and its partners — from Ukraine to Taiwan — for years to come. Why it matters: The conflict is draining weapons stockpiles far faster than American factories can replace them, leaving the Pentagon and its allies scrambling to ramp up production and find cheaper alternatives. Ukrainian President Volodymyr Zelensky wrote to President Trump this week urgently requesting interceptors to knock down expected Russian missile barrages. But Iran has taken top priority, and a new analysis suggests it will take years to replace munitions expended in that war. Breaking it down: A report from the Center for Strategic and International Studies (CSIS) finds that the U.S. used so many interceptors from missile defense systems like Patriot and THAAD in the Middle East that stockpiles won't be replenished until 2029.…