Ukraine has turned the tables on Russia in recent days by spectacularly breaching the country’s borders.
Kyiv launched its deepest raid into Russian territory last week, more than two years after Vladimir Putin ordered the invasion of its European neighbour.
It’s a significant development, considering most of the war – until now – has been fought on Ukrainian land, and has been more of a defensive mission for Kyiv.
Here’s what you need to know.
What has happened at the Ukraine-Russia border?
On Tuesday, Ukraine launched its surprise attack and advanced by more than 19 miles inside Russia, into the Kursk region.
Moscow has been unsuccessful in stopping it so far, and instead has resorted to evacuating more than 76,000 people, and declaring a state of emergency in the area.
Emergency trains sending locals from Kursk to Moscow have been set up, too.
President Volodymyr Zelenskyy only acknowledged that Ukraine’s military were pushing the war onto “the aggressor’s territory” for the first time on Saturday.
Even the US, Ukraine’s most powerful ally, said it had not been told about the attack in advance.
The UK has refused to comment on “individual operations” within the war, but Keir Starmer’s spokesperson told journalists on Monday: “Our position in regard to our support remains unchanged.”
A senior Ukrainian official also told AFP news agency that thousands of soldiers were involved in the plan, while Russia had previously suggested it was hundreds.
While Russia still controls 18% of Ukrainian land, the incident has clearly got under Moscow’s skin.
Putin declared the offensive was a “major provocation” last week, while Kursk governor Aleksei Smirnov called it a “treacherous” Ukrainian attack and Russian officials warn of a “tough” response.
Russian foreign ministry spokeswoman, Maria Zakharova, said in a statement on Sunday: “The Kyiv regime is continuing its terrorist activity with the sole purpose of intimidating the peaceful population of Russia.”
She claimed Ukraine “understands perfectly well” that these attacks “make no sense from a military point of view”.
She added that “perpetrators of these crimes ... will be held accountable for them,” and said “a tough response from the Russian Armed Forces will not be long in coming.”
Russia has sent drones and missiles to regions across Ukraine, including the capital of Kyiv, in retaliation.
What about the Zaporizhzhia nuclear plant?
The two countries are also trading blows over Europe’s largest nuclear power plant, in Zaporizhzhia, which is occupied Ukrainian territory.
The plant has not actually produced any power in more than two years and all six reactors are in cold shutdown, but it’s still a major point of tension in the war.
The plant has been a major source of concern since the conflict started in case it gets caught in the crossfire.
And now, Ukraine and Russia are blaming one another after a fire broke out at a nuclear plant’s cooling towers.
Zelenskyy has blamed the occupying Russian forces, saying it was an attempt to “blackmail” Ukraine, while the Kremlin-installed governor said it was Ukrainian shelling.
However, the UN nuclear watchdog said there was “no impact reported” for nuclear safety, although it did see “strong dark smoke” coming out of the plant.