KYIV - Last week, Ukraine launched an audacious military offensive, planned and executed in secrecy, with the aim of upending the dynamics of a war it has appeared to be losing, town by town, as Russian troops ground forward in the east.

       The operation surprised even Ukraine’s closest allies, including the United States, and has pushed the limits of how Western military equipment would be permitted to be used inside Russian territory.

       Mostly on the defensive since a failed counter-offensive in 2023, Ukraine has pushed 11km into Russia along a 40km front and taken dozens of Russian soldiers as prisoners, analysts and Russian officials say. The governor of Russia’s Kursk region said on Aug 12 that Ukraine controls 28 towns and villages there. More than 132,000 people have been evacuated from nearby areas, Russian officials said.

       “Russia brought war to others, and now it is coming home,” President Volodymyr Zelensky of Ukraine said in his Aug 12 address.

       This offensive is a major gamble, especially since Russia dominates much of the front line in Ukraine and has made significant inroads in the east. If Ukrainian troops are able to hold territory, they could stretch the capacity of Russian troops, deliver a major embarrassment for Russian President Vladimir Putin and get a bargaining chip for any peace negotiations.

       But if Russia manages to push Ukrainian troops out of Kursk and simultaneously move forward in eastern Ukraine, Ukrainian military leaders could be blamed for giving the Russians an opening to gain more ground.

       Ukrainian officials have remained tight-lipped about the mission, and military analysts who spend their days tracking the war said they were surprised.

       “This is a good example of how a modern successful operation requires extreme operational security measures and deception,” said Mr Pasi Paroinen, an analyst from the Black Bird Group, a Finland-based organisation that analyses battlefield footage.

       There were hints of what was to come.

       Maps of the battlefield compiled by independent analysts show that soldiers from brigades long fighting in the east had moved discreetly into Ukraine’s Sumy region, just across the border from Kursk.

       A few Russians noticed. A report was submitted to Russian military leadership about a month before the attack saying that “forces had been detected and that intelligence indicated preparations for an attack”, Mr Andrei Gurulyov, a prominent member of Russia’s Parliament and a former high-ranking army officer, said after the incursion.

       “But from the top came the order not to panic, and that those above know better,” he lamented on national television.

       Ukraine shuffled parts of brigades into the Sumy area under the pretences of training and picking up new equipment, said one brigade’s deputy commander, Lieutenant-Colonel Artem, who asked to be identified only by his first name and rank, in keeping with military protocol.

       The Ukrainians hid in plain sight. Officers were told to avoid wearing military uniforms when entering towns and cities so they did not draw attention, said one officer, who identified himself by his call sign, Tykhyi, in keeping with military protocol.

       Some residents noticed the build-up. “Maybe they were reinforcing the border, or maybe building something?” said Ms Elena Sima, the head of the Yunakivka district, about 8km from the border. “Everybody was guessing.”

       In Khotyn, the rumble of heavy, tracked vehicles woke up Ms Natalya Vyalina, a 44-year-old kindergarten teacher, several nights in a row. But in the village, “nobody said anything”.

       Even within the army, many were kept in the dark. Tykhyi – which means “quiet one” in Ukrainian – said some units were told of their mission only at the last moment.

       On Aug 3, Lt-Col Artem said his brigade commander summoned senior officers to a meeting on the side of a forest road to announce the mission’s goals: to divert Russian troops to help fellow soldiers fighting in the eastern Donbas region; to push Russian artillery out of range of Sumy; and to demoralise the Russians by showing their intelligence and planning failures.

       The Ukrainian military had not tried a serious push into Russia since the beginning of Moscow’s full-scale invasion in 2022. Commandos had made quick forays across the border, one in May 2023 and another this March. They were claimed by two shadowy paramilitary groups with ties to Ukraine.

       Away from the fighting, the Kursk region posed an easier target than elsewhere along the 966km front in the east and south of Ukraine, said Mr Brady Africk, an American analyst who maps Russia’s defences.

       “Russia’s fortifications in Kursk are less dense than in other areas where Russian forces have built formidable defences, such as in the south,” he said.

       Just before noon on Aug 6, the Russian authorities claimed that about 300 soldiers, more than 20 armoured combat vehicles and 11 tanks from Ukraine’s 22nd Mechanised Brigade had crossed into the country. But those initial reports were greeted with a shrug. Disinformation and propaganda have become another kind of front in this war, and no one thought such an incursion made any tactical sense.

       Hundreds more Ukrainian forces surged forward, breaching border checkpoints and pushing through two lines of defence. With fewer mines and fewer anti-military obstacles, Ukrainian mechanised brigades moved quickly.

       Oleksandr, a Ukrainian infantry soldier who declined to give his last name, citing military security protocols, said many Russian soldiers fled as the Ukrainians pushed forward. Eight Russian soldiers surrendered at one checkpoint, he added.

       “We all have joy in our hearts,” Oleksandr said in a phone interview at 5pm on Aug 8, from somewhere inside Russia. “But we realise that there are still difficult challenges ahead.”

       Some Ukrainian troops have not been able to stop themselves from publicising their moves. They have posted videos and selfies, bragging about how they have finally taken the fight to Russia.

       “Ukraine’s Kursk campaign de facto benefits,” said Mr George Barros, an analyst with the Washington-based Institute for the Study of War.

       For Russians near the border, the incursion arrived with loud booms.

       A Sudzha resident named Ivan, 34, said in a text exchange on Aug 8 that he was trying to evacuate residents. Later in the day, he wrote that he was in the hospital. His car had been hit by shelling while leaving Sudzha, home to around 6,000 people.

       “We’ve all been ditched,” Ivan said. “People are helping with whatever they can. The government doesn’t care.”

       On Aug 12, the governor of Kursk said more than 100 civilians had been injured and a dozen killed, although the figures could not be independently verified.

       The New York Times reviewed several satellite images captured since Aug 6 that showed at least two dozen structures were damaged or destroyed in Sudzha and a neighbouring village, Goncharovka, including homes, an apartment building, a petrol station and support buildings of an arts school.

       As the incursion expanded, the city of Kursk filled with people fleeing the fighting, independent political activist Yan S. Furtsev, 38, said in an interview.

       “There are a lot of different opinions” about the war, Mr Furtsev said.

       “But as for what people think, everyone believes that this is a tragedy.” NYTIMES