Brussels: NATO Secretary-General Anders Fogh Rasmussen said on Thursday he was concerned about developments in Ukraine`s Crimea and urged Russia not to do anything that would "escalate tension or create misunderstanding". Armed men earlier seized the regional government headquarters and parliament on Ukraine`s Crimea peninsula and raised the Russian flag. "I`m concerned about developments in Crimea. I urge Russia not to take any action that can escalate tension or create misunderstanding," Rasmussen said on Twitter.