NATO Secretary-General Anders Fogh Rasmussen told Russian leaders in Moscow a unified missile defense option wasn't feasible.
"I do not think the most efficient way would be to have a unified, integrated system," he was quoted by Russia's state-run news agency RIA Novosti as saying. "The right way forward would be to have a Russian system and a NATO system but to make sure that these two systems work together."
NATO in December joined Russian forces in a computer simulation dubbed Vigilant Skies 2012 that was aimed at coordinating airspace security over Eastern Europe. NATO said the simulation could pave the way to live drills over the Black Sea this year.
The drill was part of an initiative launched in 2002 that envisions greater transparency and confidence between both sides. The Russian news agency reports that bilateral missile defense initiatives have faltered because NATO hasn't provided assurances about the security of Russian interests in the region.
Similar concerns have been directed at the U.S. military. Russian President Vladimir Putin said a U.S. missile defense system in Eastern Europe would upset the regional balance of power.
Notable deaths of 2014 [PHOTOS]