Russian authorities have attempted to shift the blame on to Ukraine for a deadly attack claimed by ISIS in a Moscow concert hall which killed at least 130 people and wounded 150 others, many of whom are in a critical condition.
The claims have triggered a sharp rebuttal from the Ukrainian President Volodymyr Zelenskyy, who accused Russian President Vladimir Putin of trying "to exploit more of these situations for personal power".
Further stoking tension between the two countries were a barrage of Russian missiles and drones that rained down on Kyiv on Sunday and also violated Polish airspace.
Russian politicians have tried to link these attacks on Ukraine, which have ramped up in the wake of the recent presidential election, to the concert hall killings.
"For the victims of the mass shooting in Moscow, our comrades open fire on the enemy," wrote senator Dmitry Rogozin on X.
The Russian claims come despite ISIS's Afghanistan affiliate saying it perpetrated the attack against the Crocus City Hall, located in Krasnogorsk, north-west of the Russian capital, as part of "the raging war" with "countries fighting Islam".
The group, which operates mainly in Syria and Iraq but also in Afghanistan and Africa, has also claimed several attacks in Russia’s volatile Caucasus and other regions in the past years. It recruits fighters from Russia and other parts of the former Soviet Union.
On March 7, the US embassy in Russia had warned of the possibility of ISIS targeting concert halls in Russia. The warning was dismissed earlier this week by Mr Putin, who described it as "explicit blackmail".
The US has said it has seen no sign of Ukrainian involvement in the attack.
'Inhumane tragedy'
Russia is observing a national day of mourning after what is now the deadliest single ISIS-claimed attack on European soil. The 2015 Paris attacks killed 90 people at the Bataclan concert hall and 40 people in other locations in the French capital.
"The whole country is in mourning with those who lost their loved ones in this inhumane tragedy," the public television channel Russia 24 said on Sunday.
In his first public comments on the attack more than 18 hours after it took place, Mr Putin made no reference to ISIS.
"All the perpetrators, organisers and those who ordered this crime will be justly and inevitably punished," he said.
Russia's Investigative Committee, which probes major crimes, said many victims died of gunshot wounds and smoke inhalation after a fire engulfed the 6,000-seater venue.
"The terrorists used a flammable liquid to set fire to the concert hall's premises, where spectators were located, including wounded," the Investigative Committee said.
The Moscow Region’s Emergency Situations Ministry posted a video on Sunday showing equipment dismantling the damaged music venue to give rescuers access.
In Moscow, residents stood in long queues in the rain to donate blood for those in hospital, and mourners came to lay flowers outside the concert hall.
Memorial posters featuring a single candle replaced some advertising billboards in the capital and major events were cancelled across the country.
Museums, theatres and cinemas announced their closure over the weekend.
ISIS has released footage of the attacks on Friday, in which individuals with blurred faces and garbled voices, armed with assault rifles and knives, appear to be in the lobby of the Crocus City Hall concert venue.
The video appeared on a Telegram account thought to belong to Amaq, the news arm of ISIS, according to the SITE intelligence group.
An attack 'for money'
Russian television showed security services interrogating four bloodied men, who spoke Russian with an accent, on a road in the western Bryansk region, which borders both Ukraine and Belarus.
"They tried to escape and were travelling towards Ukraine, where, according to preliminary data, a window was prepared for them on the Ukrainian side to cross the state border," said Mr Putin.
In the videos, two handcuffed suspects admit to the attack but do not say who organised it.
One handcuffed man on his knees tells an interrogator off-camera that he did it "for money", with the amount being 500,000 Russian roubles ($5,423).
The men do not confirm their nationality but reports point to them originating from Tajikistan, a mainly Muslim Central Asian state that used to be part of the Soviet Union.
Tajik authorities have so far not confirmed these reports, which were first propagated by the Russian politician Alexander Khinshtein, who said Tajik passports had been found in the car of those arrested.
ISIS has claimed numerous attacks on Russian interests in the past, including the 2015 bombing of Metrojet Flight 9268, which killed 224 people flying to St Petersburg from the Egyptian resort of Sharm el-Sheikh.
