KYIV: Ukrainian leader Volodymyr Zelensky spoke of “good news” on the battlefields of eastern Ukraine, saying his army had retaken some towns and villages from Russia in what open source analysts said looked like a deep and sudden thrust behind Russian lines.In his daily late night address on Wednesday, President Zelensky said he had received news that his forces had liberated a slew of settlements in the Kharkiv region in a counter offensive that some Western analysts suggested had seen Kyiv recapture around 400 square kilometers (154 square miles) of territory.”This week we have good news from Kharkiv Oblast. All of you have most likely seen reports about the recent activities of Ukrainian defenders. And I think every (Ukrainian) citizen feels proud of our warriors,” said Zelensky.Kharkiv region borders Russia and its main city, Kharkiv, has for months been struck by Russian missiles after Moscow failed to take it in the early stages of its Feb. 24 invasion.In a sign that the situation in the area was still highly fluid though, Zelensky said it was too early to name the recaptured towns and villages while thanking two airborne brigades and a mechanized brigade for what he called their bravery.Such a thrust, if confirmed and the gains are held, would be a significant boost for Kyiv, which is keen to show its Western backers that it can change the facts on the ground by force and deserves continued financial and weapons support.There is additional pressure on Kyiv to demonstrate that before winter sets in amid threats by Russian President Vladimir Putin to halt all energy shipments to Europe if Brussels goes ahead with a proposal to cap the price of Russian gas.In a boost for Kyiv, US Defense Secretary Lloyd Austin said on Thursday that President Joe Biden had approved an additional $675 million in weapons to Ukraine as he and other defense ministers met in Germany to discuss how to continue supporting Ukraine in the long-term.The Institute for the Study of War (ISW), a Washington-based think tank, which follows the war day-by-day, said the Ukrainian military looked to have made significant progress on Wednesday.”Ukrainian forces likely used tactical surprise to advance at least 20 km into Russian-held territory in (the) eastern Kharkiv Oblast (region) on September 7, recapturing approximately 400 square kilometers of ground,” the ISW said.Russia has confirmed fighting in the area but has not confirmed any territorial losses, though unverified social media accounts run by Russian military experts have suggested Moscow did suffer setbacks and will need to urgently reinforce.Ukrainian Presidential adviser Oleksiy Arestovych, in a video posted on YouTube, said Ukrainian troops had surprised Russian defenders at the town of Balakleiia.”The Russians are saying that Balakleiia is encircled when in fact (our troops) have gone much further.”A pro-Russian official from the region, Rodion Miroshnik, said on Telegram that Balakleiia remained in Russian hands although there was fighting north of the town.Reuters was unable to verify the battlefield accounts but Yuri Podolyak, a Ukrainian often quoted by pro-Russian officials, also said Russian troops were surprised by the Ukrainian advance.”The enemy had considerable success near Balakleiia with a relatively small force … It would appear that Russian forces slept through this advance and were expecting it elsewhere,” he wrote on Telegram.”Everything would seem to depend now on the speed with which reserves are brought into the fight … there have been significant losses.”