Medvedev said North Korea's underground nuclear explosion last month and the test-firing of a long-range missile have increased concerns about nuclear proliferation, the Russian news agency RIA Novosti reports.
He said it was necessary to very closely monitor "borderline states" that are developing nuclear weapons without an international mandate.
"I expect to discuss the issue with the U.S. president soon," Medvedev said during a break in an economic forum in St. Petersburg.
Earlier the Russian leader said he was ready to support economic sanctions aimed at deterring North Korea's nuclear program.
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