Huge diplomatic efforts and punitive worldwide sanctions on Russia are being taken by the PM and other foreign leaders to get Putin to exit the Ukraine and return the Black Sea region to a greater sense of peace. There is targeting of banks, individuals, and organisations: this is clearly impacting on Russia. My hope is that Putin will change course and return to peaceful coexistence rather than continue to create division and divide locally on Russia's doorstep - effectively partitioning Ukraine in an illegal act of invasion. No one wants to return to the Cold War but Russia cannot act in this way. Good to see the World leaders acting as one - the G20 was particularly impressive on the Ukraine Problem. Those who want to read and know more the BBC has done a detailed appraisal:
http://www.bbc.co.uk/news/world-europe-28400218
More details on the PMs approach found here: http://www.telegraph.co.uk/news/worldnews/vladimir-putin/11232832/David-Cameron-Putin-is-not-a-man-of-his-word.html