"We take a negative view of NATO enlargement. The problem is that new military infrastructure is being built around Collective Security Treaty Organization [CSTO] member states, primarily Russia and Belarus," Nikolai Bordyuzha, general secretary of the CSTO, told a news conference in the Armenian capital.
The CSTO is a post-Soviet security alliance which also comprises Armenia, Belarus, Kazakhstan, Kyrgyzstan, Uzbekistan, and Tajikistan.
"This also applies to forward bases in Bulgaria and Romania, attempts to deploy radar stations in the Baltic region, and infrastructure in Central Asia," he said.
Bordyuzha said the expansion of NATO would not automatically bring about greater stability in the world.
"I believe there are other ways of creating collective security systems, both in Europe and globally; these options should be used," he said. He also added, without elaborating, that it was wrong "to impose NATO membership on certain states."
He conceded, however, that any sovereign state had a right to join any international organization, as long as that "strengthens global stability."
He stressed that all post-Soviet states needed stability to be able to continue their economic growth and implement social programs.
"It is this kind of stability that we are working for, including through the CSTO," Bordyuzha said.
Russia has been strengthening military ties with its allies amid growing tensions over NATO expansion and U.S. missile shield plans for Central Europe. An agreement was recently signed by Washington and Prague on deploying a U.S. radar in the Czech Republic, a move that did little to assuage Russian concerns for its national security. The missile deal has yet to be approved by the Czech parliament.