WASHINGTON — The Pentagon’s most recent package of weapons for Ukraine includes relics from the Cold War to help blunt Russian advances and limit their ability to maneuver during an expected spring offensive. Those weapons, M21 anti-tank land mines, have been in service with the Defense Department since at least the early 1960s. An unknown number of them will be sent to Ukraine as part of a $325 million package of aid from U.S. military stockpiles that was announced this week, the 36th such transfer of lethal matériel to Kyiv since August 2021. M21 mines — large metal-bodied weapons that are usually buried and explode when a vehicle drives over them — contain a specialized warhead built to punch through inches of armor plating. “Anti-tank land mines are an important defensive capability against Russia’s tanks and armored vehicles, helping Ukraine’s forces repel Russia’s attacks and shape the battlefield to Ukraine’s advantage,” Maj. Charlie Dietz, a Pentagon spokesman, said in a statement on Thursday.

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