Secretary of State Antony Blinken said Monday the U.S. government will return its diplomats to Ukraine starting this week with a new ambassador set to be nominated for the post, while assessing that Russia has “failed” in its war against the East European country. He made the remarks in Poland after visiting Kyiv with Defense Secretary Lloyd Austin a day before, the first such trip by high-level officials in the administration of U.S. President Joe Biden since Russia began its invasion of Ukraine in late February. Touching on a meeting with Ukrainian President Volodymyr Zelenskyy in the capita…