U.S. President Barack Obama blamed Russia on Sunday for the fighting that has flared anew between government troops and separatists in eastern Ukraine, and said the United States would consider additional options to ratchet up pressure on Moscow. "We will continue to take the approach that we have taken in the past, which is to ratchet up the pressure on Russia," Obama told a news conference in New Delhi. "And I will look at all additional options that are available to us, short of military confrontation, and try to address this issue." Fighting has flared in Ukraine in recent days after the rebels ruled out more peace talks. Russia, which the West accuses of supporting the separatists, prevented the U.N. Security Council on Saturday from criticising rebel statements and condemning the upsurge in violence.