Volodymyr Zelenskiy has said Ukraine’s military incursion into Russia’s Kursk region aims to create a buffer zone to prevent further attacks by Moscow across the border.

It marked the first time the Ukrainian president had clearly stated the aim of the operation, which was launched on 6 August. Previously, he had suggested it aimed to protect communities in the bordering Sumy region from constant shelling.

In his nightly address on Sunday, Zelenskiy said: “It is now our primary task in defensive operations overall to destroy as much Russian war potential as possible and conduct maximum counteroffensive actions. This includes creating a buffer zone on the aggressor’s territory – our operation in the Kursk region.”

Kyiv had previously said little about the goals of its push into Russia with tanks and other armoured vehicles, the largest attack on the country since the second world war, which took the Kremlin by surprise and led to scores of villages and hundreds of prisoners falling into Ukrainian hands.

The Ukrainians drove deep into the region in several directions, facing little resistance and sowing chaos and panic as tens of thousands of civilians fled.

Ukraine’s commander in chief, Gen Oleksandr Syrskyi, claimed last week that his forces had advanced across 1,000 square kilometres (390 square miles) of the region, although it was not possible to independently verify how much territory Ukrainian forces effectively control.

In his remarks on creating a buffer zone, Zelenskiy said Ukrainian forces “achieved good and much-needed results”.

For his part, Russia’s president, Vladimir Putin, said during a visit to China in May that Moscow’s offensive that month in Ukraine’s north-eastern Kharkiv region was aimed at creating a buffer zone there.

That offensive opened a new front and displaced thousands of Ukrainians. The attacks were a response to Ukrainian shelling of Russia’s Belgorod region, Putin said. “I have said publicly that if it continues, we will be forced to create a security zone, a sanitary zone,” he said. “That’s what we are doing.”