"There's no doubt that Russia is heavily engaged in destabilizing eastern Ukraine, and they continue their activities," said Rasmussen.
Speaking in unusually blunt terms, Mr. Rasmussen warned the West not to be fooled by moderate statements by President Vladimir V. Putin, who he said was trying to fend off another round of economic sanctions. "Don't make any mistake, it's pure tactics," Mr. Rasmussen said. "He keeps open the option to intervene if necessary."
Russia, Mr. Rasmussen said, was waging what he called "hybrid warfare," a combination of military action, covert operations and an aggressive program of disinformation - all calculated to weaken Ukraine's new government and leave its eastern part under Russian influence. Mr. Rasmussen said it was likely that separatist fighters had used Russian antiaircraft weapons to shoot down Ukrainian planes and helicopters.