NATO Thursday urged Russia not to take any action which could escalate tension or create misunderstanding in Ukraine.
"NATO has a long-standing partnership with Ukraine. Today we made clear that NATO stands ready to support democratic development, defence reforms, military cooperation and democratic control over the security sector," Xinhua quoted NATO Secretary General Anders Fogh Rasmussen as saying.
Rasmussen expressed concern over recent developments in Ukraine's Crimea region. "This morning's action by an armed group is dangerous and irresponsible," he said. "I urge Russia not to take any action that could escalate tension or create misunderstanding."
"There is a need for all concerned to take a responsible stance and to work for stability," he said.
Armed men seized the regional government headquarters and parliament in Ukraine's Crimea Thursday and raised the Russian flag.
A two-day meet of NATO defence ministers started Wednesday in Brussels, with defence capabilities, Afghanistan and Ukraine on top of the agenda.