Humiliation for Putin as Ukrainian troops smash through Russian border ahead of VE Day

has reportedly launched a new offensive in 's Kursk region in a major embarrassment for Vladimir Putin. The Kremlin had been determined to expel all Ukrainian forces from Russian territory ahead of this week's . Mr Putin had announced a three-day ceasefire with Ukraine, from Thursday to Saturday, to mark the 80th anniversary of the Soviet Union's defeat of Nazi Germany in World War 2.

But Ukrainian President Volodymyr Zelensky's troops breached the Russian border on Sunday night near the village of Tetkino, triggering heavy clashes inside Russia itself. Mr Zelensky has said he had no faith in Moscow's willingness to honour any truce, warning: "We understand who we are dealing with: we do not believe them."

Russian Telegram channels claimed that Ukrainian units had fired missiles, crossed minefields and stormed through defensive lines near the border.

One pro-war blogger reported "a heavy battle going on at the border," with bridges, factories and civilian infrastructure badly damaged.

Another source claimed around 50 Ukrainian troops had entered Kursk, with fighting also breaking out near the village of Zvannoe.

Local lawmaker Alexander Khinstein confirmed the assault had killed three people.

There was no immediate comment from either Kyiv or Moscow, though 's commander-in-chief, Oleksandr Syrsky, later said the operation had "achieved most of its goals."

The latest fighting represents a major blow to Mr Putin, just days after Russian forces claimed to have recaptured full control of the Kursk region, where Ukraine had previously staged another daring incursion last year.

Officials in Kyiv believe the border assault is likely to place renewed pressure on Russia's overstretched troops, even as Moscow continues to resist proposals for an unconditional ceasefire.

Despite recent gains, Russia continues to occupy around 20% of Ukrainian territory, including Crime,a which it seized in 2014.

Meanwhile, thousands of North Korean fighters have reportedly arrived in southern Ukraine to support Russian forces in their push to reverse Ukraine's recent advances.

The timing of the latest incursion has undermined Mr Putin's efforts to project strength during the run-up to Victory Day, one of Russia's most important national events.

Friday's parade on Moscow's Red Square is expected to feature tanks, missiles and military flypasts in a show of strength marking the end of the Great Patriotic War.

Chinese President Xi Jinping is expected to attend, further underlining the Kremlin's efforts to rally international allies. However, with war on its doorstep and Ukrainian troops inside its borders, the message of military might may ring hollow.