Ukrainian troops sprang one of the biggest surprises of the war by invading Russia's Kursk region last August, and Russia has taken more than seven months to eject them.
Here is a timeline of the fighting there and what both sides have said about it.
August 6, 2024: Ukrainian troops smash across the border in the biggest foreign attack on Russia since World War Two. The incursion hands Ukraine its biggest battlefield gains since 2022, after months on the back foot. Russia rushes in reserve troops, and nearly 200,000 Russian civilians are forced to flee their homes.
August 10: Ukrainian President Volodymyr Zelenskiy, in his first public comments on the operation, says Ukraine is proving it can "restore justice" and pile "pressure on the aggressor".
August 12: Russian President Vladimir Putin says the Ukrainian operation is a bid to undermine Russia's stability, slow its advance elsewhere and improve Kyiv's negotiating position. Russia will deliver a "worthy response", Putin says. U.S. Republican Senator Lindsey Graham calls the Ukrainian incursion "bold, brilliant, beautiful".
August 13: Russia strikes back in Kursk with missiles, drones and air strikes as fierce fighting rages. Ukraine says it is still advancing. Russia's rouble hits a 10-month low. U.S. President Joe Biden says the incursion has created a "real dilemma" for Putin.
August 19: Zelenskiy says his forces control more than 1,250 sq km (500 sq miles) and 92 settlements. He says the operation proves that Russia's "so-called red lines", meant to deter the West, are a bluff.
August 27: Russia says U.S. involvement in Ukraine's incursion is an "obvious fact". Washington says it was not informed in advance and took no part.
September 2: Putin says Russian forces are advancing much faster in eastern Ukraine - something Kyiv's incursion was intended to prevent. Zelenskiy acknowledges the situation in the east is difficult but says the Kursk operation is going according to plan.
September 10: Russia says it has begun a significant counter-offensive in Kursk and recaptured about 10 settlements.
October 14: Zelenskiy says Ukrainian forces are "standing firm" in Kursk and have repelled five straight days of Russian attempts to break through their lines. Two days later he unveils a "Victory Plan" that includes a continuation of Ukrainian operations in Kursk.
October 23-30: Ukraine and its allies say at least 11,000 North Korean troops have been sent to Russia to join the war on Moscow's side.
November 20: Ukraine fires British Storm Shadow cruise missiles, which London had previously allowed it to use only within its own territory, into Kursk region.
November 24: A Ukrainian military source says Ukraine has lost over 40% of the territory it captured in Kursk. It now controls about 800 sq km, down from a peak of 1,376, the source says.
December 14: Zelenskiy says significant numbers of North Korean troops are taking part in Russian attacks in Kursk.
December 19: Putin says Kursk will be "liberated" but declines to set a target date.
December 27: The White House says North Korean troops in Kursk are being treated as "expendable" and 1,000 have been killed or wounded in the previous week.
January 5-7, 2025: Russia says it has repelled a new Ukrainian attack in Kursk region. Ukraine says it is conducting "new offensive actions".
January 11, 2025: Zelenskiy says two North Korean soldiers have been captured alive on the battlefield.
February 6: Russia says its troops have repelled a Ukrainian counteroffensive in Kursk region. Six months after the incursion, Zelenskiy says the operation "brought the war home for Russians so that they might feel just what war is. And they are feeling it".
February 11: Zelenskiy says he is ready to swap parts of Kursk held by Ukraine for Ukrainian land captured by Russia; the Kremlin says Moscow will never discuss this.
February 13: Ukraine says it now holds 500 sq km in Kursk.
February 20: A Russian general says Russian forces have taken back more than 800 sq km, or about 64% of the total that Ukraine had captured.
March 3-5: U.S. President Donald Trump suspends military aid and intelligence-provision for Kyiv, days after an angry clash with Zelenskiy at the White House.
March 7: Military analysts say Ukrainian forces in Kursk are nearly surrounded after a sharp worsening of their position.
March 9: Russia says its forces take three more settlements after special forces crept for miles through a gas pipeline near the town of Sudzha to surprise Ukrainian forces.
March 10: Ukraine's top general denies his forces in Kursk are at risk of being encircled but says they are taking up better positions for defence.
March 11: Russia says its forces have made more gains, capturing over 100 sq km and a dozen settlements.
