Ukrainian drones struck Moscow on Tuesday but were neutralised, Russia said in what one politician called the worst attack on the capital since World War Two, while Kyiv was also hit by air for the third time in 24 hours.
Since Russia sent troops into its neighbour in February last year, the war has largely been fought inside Ukraine, though Moscow has reported some attacks on its territory including an alleged assassination attempt against President Vladimir Putin.
Moscow Mayor Sergei Sobyanin said the early morning drone assault had injured two people, while some residents in two lightly damaged apartment blocks were briefly evacuated.
Russia's defence ministry said eight drones sent by Kyiv were shot down or diverted, though Baza, a Telegram channel with links to the security services, said more than 25 were involved.
Residents said they heard loud bangs followed by the smell of petrol. Some filmed a drone being shot down and a plume of smoke rising over the Moscow skyline.
Lawmaker Maxim Ivanov termed it the most serious assault on Moscow since the Nazis, saying no citizen could now avoid "the new reality". "You will either defeat the enemy as a single fist with our Motherland, or the indelible shame of cowardice, collaboration and betrayal will engulf your family," he said.
Two weeks ago, two drones exploded over the Kremlin in an attack Russia also blamed on Kyiv and said was aimed at Putin.
Ukrainian presidential aide Mykhailo Podolyak denied Kyiv was directly involved in targeting Moscow on Tuesday, though he said "we are pleased to watch" and forecast more to come.
At a messy stalemate for most of 2023 with Russian troops occupying some eastern Ukrainian regions, the war has killed tens of thousands, uprooted millions, reduced cities to ruins and caused havoc in the global economy.
Kyiv hight-rise hit
In Kyiv, Ukrainian defence forces said they shot down more than 20 Iranian-made Shahed drones on Tuesday.
One person died and four were injured when debris from a destroyed Russian projectile hit a high-rise apartment building causing a fire, Ukrainian officials said. Two upper floors were destroyed with people possibly still under rubble.
Photos from Kyiv officials and Reuters reporters showed flames engulfing the top of the building. "The attack was massive, came from different directions, in several waves," said Serhiy Popko, head of Kyiv's military administration.
Russia has attacked Kyiv 17 times in May with drones or missiles, mostly at night, in an apparent attempt to undermine Ukrainians' will to fight after more than 15 months of war.
"These missile attacks of a fairly dense frequency are aimed specifically at exhausting both our air defence forces and our physical and moral strength," said Natalya Gumenyuk, a spokesperson for Ukraine's southern military command.
President Volodymyr Zelensky said US-supplied Patriot anti-missile defences were achieving a 100% interception rate.
"Terror will be defeated," he said in his nightly address on Monday.
Ukraine is promising a counter-offensive backed with Western weapons to try to drive Russian occupiers from territory seized since Moscow launched its "special military operation".
On the eastern front lines, Russian paratroops and motorised units were replacing Wagner mercenary units in the city of Bakhmut, which has been the main focus of fighting for months, according to a Ukrainian military representative.
Moscow said it invaded Ukraine to "denazify" its neighbour and protect Russian speakers. Western opponents say the invasion is an imperialist land grab.
Moscow says it is open to resuming stalled peace talks with Kyiv and has welcomed mediation efforts from Brazil and China.
But Kyiv insists full withdrawal of Russian troops is the only way to end the war.