>> but the u.s. president says vladimir putin chose this war and must therefore bear the consequences, imposing the harshest sanctions yet on russia. >> putin's aggression against ukraine will end up costing russia dearly economically and strategically. we will make sure of that. putin will be a pariah on the international stage. any nation that countenances russia's naked aggression against ukraine will be sustained by association. >> cnn's matthew chance and his crew travelled to an airfield outside kyiv on thursday and ended up witnessing a major confrontation, russian special forces deployed to the area by helicopter and exchanging fire with ukrainian troops. >> how can i film it?