SEOUL, South Korea — North Korea’s Kim Jong Un rolled through Russia on an armored train Tuesday toward a meeting with President Vladimir Putin, a rare encounter between isolated leaders driven together by their need for support in escalating standoffs with the West.

       Kim is expected to seek economic aid and military technology for his impoverished country, and, in a twist, appears to have something Putin desperately needs: munitions for Russia’s grueling war in Ukraine.

       It’s a chance for the North Korean leader to get around crippling U.N. sanctions and years of diplomatic isolation. For Putin, it’s an opportunity to refill ammunition stores that the war has drained.