By Humeyra Pamuk BUCHAREST (Reuters) – U.S. Secretary of State Antony Blinken on Tuesday will announce new assistance to help restore Ukraine’s power transmission ability in the face of Russian attacks targeting the country’s energy grid, a senior State Department official said. Blinken arrived in Romania on Monday evening ahead of a meetings with NATO allies and foreign ministers from the Group of Seven advanced economies. Ukraine’s foreign minister told some NATO diplomats visiting Kyiv earlier in the day that transformers were the biggest element of the country’s power infrastructure that n…