LIVERPOOL, England, Dec 11 (Reuters) - The United States will send its top diplomat for Europe to Russia and Ukraine to discuss Russia’s troop build up and reiterate U.S. commitment to Ukraine’s sovereignty, the State Department said on Saturday. "Assistant Secretary for the Bureau of European and Eurasian Affairs, Dr. Karen Donfried will travel to Kyiv, Ukraine and Moscow, Russia December 13-15 to meet with senior government officials to discuss Russia’s military buildup and to reinforce the United States’ commitment to Ukraine’s sovereignty, independence, and territorial integrity," the department said. "Donfried will emphasize that we can make diplomatic progress on ending the conflict in the Donbas through implementation of the Minsk agreements in support of the Normandy Format."