It was an "accident."
That was Moscow's official response to how a group of Russian paratroopers ended up in Ukraine. The soldiers -- apparently from a division based in Kostroma, a city on the Volga River north of Moscow -- were captured by Ukrainian forces, who posted videos of some of their interrogations online.
In what appear to be forced confessions in front of Ukrainian military personnel, they say they were misled by their superiors, who told them they were going on a "training exercise."
The videos appeared to confirm what Kyiv authorities had been claiming for months amid denials from the Kremlin -- that Moscow is supplying pro-Russian separatists with military hardware and personnel.
The claims had largely been based on circumstantial evidence. But since mid-August, as Russia has attempted to staunch Ukrainian gains against the militants, that evidence has mounted steadily.
WATCH: In a video released by the Ukrainian Security Service, three Russian soldiers describe entering Ukraine.
On August 14, journalists from two British newspapers reported seeing an armored convoy enter Ukraine from the Russian side of the border. Moscow said the reporters' claims were "not true."
The next day, Ukrainian President Petro Poroshenko claimed that Ukrainian forces had "destroyed" the convoy. Moscow called the claim, still unverified, a "phantom" act.
Then, on August 25 a mysterious funeral was held for two paratroopers in Pskov, according to Russian media reports. Moscow has not commented.
And now there is the case of the 10 paratroopers, and the video evidence presented by the Ukrainian authorities.
Kyiv says there are 10 Russian captives in all. Ukrainian officials released videos of four of them early on August 26. In separate interrogations, the young men's faces appear slightly swollen. Their answers appear designed to please their captors.
Moscow, for the first time confirming the presence of Russian troops in Ukraine, admitted that the men were indeed its servicemen. But it says their presence there is mere happenstance.
They crossed the border "by accident at an unequipped and unmarked zone, and as far as I know they didn't resist the armed forces of Ukraine," an unidentified source from Russia's Defense Ministry told the RIA Novosti state news agency.
A satellite view of the border area near Amvrosiyivka, where Kyiv says the soldiers were apprehended, shows most of the border marked by hedgerows, although there are some narrow gaps.
The Russian explanation comes a day after a closed military funeral held in Pskov, some 1,600 kilometers from Ukraine's separatist-controlled eastern border with Russia. There, according to reporting by the independent Slon.ru website and "Pskov Province," a local publication, families buried Leonid Kichatkin and Aleksandr Osipov.
Photos show two Russian Orthodox crosses, about 10 meters apart -- both covered in floral wreaths. Osipov's gravestone engraving says he died on August 20 and Kichatkin on August 19. There is no information about how or where they died.
A Ukrainian journalist for Inter Television had posted a series of photos to his Facebook page on August 21, including documents and weapons parts -- allegedly taken after fighting in Luhansk. The journalist wrote that the material could be traced back to a Pskov paratrooper division, and thus present circumstantial evidence that the soldiers had died fighting in Ukraine.
Among the photos is the driver's license of Ilya Maksimov, a paratrooper serving in a Pskov paratrooper division. Speaking to reporters from the southern Russian city of Saratov, his mother, Lyubov Maksimova, said she had lost contact with her son on August 17. He had told her he would be conducting military operations near Rostov -- the closest city to Ukraine's eastern border.
Russian President Vladimir Putin and Poroshenko met on August 26 in Minsk with EU mediators to discuss a solution to the conflict, which began in April, when armed militants began seizing buildings in Ukraine's Donetsk and Luhansk regions. The conflict has since claimed over 2,000 lives.
But in what could be a sign for Kyiv that the presence of paratroopers in Ukraine is more than just a single Russian volley, new fighting has broken out in the Ukrainian city of Novoazovsk -- well outside the zone of territory currently controlled by separatists.
Lying on the Azov Sea, just 12 kilometers from the Russian border, it is on the road that leads to the Ukrainian port city of Mariupol and then on to Crimea, which Russia annexed in March.
Kyiv has accused Russia of shelling the city from its side of the border and a commander of Ukraine's Azov Battalion claimed on Facebook on August 25 that a convoy of 50 armored vehicles had crossed into Ukrainian territory and had attempted to reach Mariupol.
And in an unconfirmed charge, Andriy Lysenko, a spokesman for Ukraine's National Security and Defense Council, said Russian troops had also begun using helicopters to fire missiles at Ukrainian positions for the first time, killing four border guards in an attack.
Lysenko dismissed Moscow's most recent denials. "We think it was not a mistake, it was a special mission," he said of the captured paratroopers. "The Russian military leadership must think about what they are doing."