There is a greater sense of urgency at Sunday's defence summit held in London than the Munich Security Conference last month after the blowout between the US and Ukraine Friday, said Olena Prokopenko, Senior follow at the German Marshall Fund. “We saw that the US might be finalising its shift towards Russia unfortunately in terms of the peace talks and the position that it’s taking”, Prokopenko said, adding that Europe has an important role to play in "mediating between Ukraine and the US".