Kyiv : Ukrainian forces on Sunday pushed its counteroffensive in the country’s east, exploiting quick gains they made in a week of fighting that has sharply changed the course of the conflict.Ukraine’s quick action to reclaim Russia-occupied areas in the northeastern Kharkiv region forced Moscow to withdraw its troops to prevent them from being surrounded and leave behind significant numbers of weapons and munitions in a hasty retreat as the war marked 200 days on Sunday. The jubilant Ukrainian President Volodymyr Zelenskyy mocked the Russians in a video address late Saturday, saying that “the Russian army in these days is demonstrating the best that it can do — showing its back.” The Russians’ pullback marked the biggest battlefield success for Ukrainian forces since they thwarted a Russian attempt to seize the capital, Kyiv, at the start of the nearly seven-month war.In an awkward attempt to save face, the Russian Defense Ministry said the troops’ withdrawal from Izyum and other areas in the Kharkiv region was intended to strengthen Russian forces in the neighboring Donetsk region to the south.The claim sounded similar to the justification Russia gave for pulling back its forces from the Kyiv region earlier this year when they failed to take the capital.The group of Russian forces around Izyum has been key for Moscow’s effort to capture the Donetsk region, and their pullback will now dramatically weaken the Russian capability to press its offensive there.The retreat drew angry comments from Russian military bloggers, who bemoaned it as a major defeat and urged the Kremlin to respond by stepping up war efforts. Many scathingly criticized Russian authorities for continuing with fireworks and other lavish festivities in Moscow that marked a city holiday on Saturday despite the debacle in Ukraine.