Along with the stern warnings, Medvedev repeatedly said Russia is still willing to discuss their concerns with a more receptive audience.
"But let me stress the point that we are not closing the door on continued dialogue with the USA and NATO on missile defense and on practical cooperation in this area. We are ready for that," he said.
A NATO spokesperson said that while Medvedev's threats to move offensive missiles near Russia's European borders was "not helpful," the international organization "welcomed" Medvedev's willingness to continue to discuss the issue, according to a report by Reuters.
ABC News' Devin Dwyer contributed to this report.