The leaders of the United States and the United Kingdom have both accused Russia of staging "false flag" operations to discredit the Ukrainians and create a pretext for invading Ukraine.
Ukrainian forces and pro-Moscow rebels clashed in the Donbas separatist region on Thursday, but both sides gave conflicting accounts of the conflict.
While Ukraine said separatists had shelled its forces — but they did not fire back — and some of those shells hit civilian houses and a kindergarten in Stanytsia Luhanska, wounding two teachers and cutting power to half of the town.
Russia’s Deputy Foreign Minister, Sergey Vershinin, accused Kyiv of repeated attacks on Russian separatist-controlled territory in eastern Ukraine, causing "thousands of victims".
"Attempts to place the blame on Russia are futile and baseless" and aim at "shifting of the blame away from Ukraine", Mr Vershinin said.
Although the kindergarten that was hit is in Ukrainian government-held territory, British Prime Minister Boris Johnson called the shelling a "false flag" operation by Russia.
But what is a "false flag" and how could Russia use this as pretext for invading Ukraine?
What is a 'false flag' operation?
A false-flag operation is a staged attack were the source of responsibility is disguised or fabricated in order to pin blame on another party.
It's a form of propaganda or disinformation that has been used for centuries as a pretext for war.
It can take the form of an elaborate military attack, where one side may dress in the uniforms of their enemies, drive the same vehicles or use the same weapons, firing them from positions that will make the attack appear to have been carried out by the other side.
Nazi soldiers were accused of carrying out numerous false-flag operations during World War II.
In one such incident in 1939, Nazi operatives, dressed as Polish soldiers, stormed a radio tower on the German-Polish border and broadcast a short anti-German message in Polish before leaving.
This, coupled with around two dozen similar incidents, were declared a "Polish assault" on Germany, and Hitler launched an invasion the following day.
The US were also accused of faking a Vietnamese attack on their own naval ship in 1964 in the lead-up to the Vietnam War.
Over the past decade of conflict in Syria, there have been repeated claims that videos of chemical and missile attacks on civilians were faked by opposing sides, using actors and fake blood, in another form of false-flag propaganda.
But the truly successful false-flag attacks are the ones we'll never hear about, according to Alexey Muraviev, a national security and strategic expert at Curtin University.
While the history of war is dotted with successful and unsuccessful false-flag attacks, there are also numerous accusations of such tactics that may never be proven.
Could the attack on a kindergarten be a false flag?
The recent shelling took place in the region of Donbas, which is partly controlled by the Ukrainian government and partly held by Russian-backed separatists who are vying for independence from Ukraine.
Stanytsia Luhanska, where a kindergarten was shelled on Thursday, lies in Ukrainian government-held territory, while some neighbouring towns are held by the separatists.
While claims of a Russian false-flag operation in this particular instance appear to be unfounded, Dr Muraviev said the situation was complex.
Confrontation in this area is not directly between Russia and Ukraine, but between pro-Russian separatists and Ukrainian forces.
Speaking the same language and having access to the same weapons means "it wouldn't take much effort" for either side to "effectively stage a false-flag operation", according to Dr Muraviev.
"This certainly gives the Kremlin sufficient grounds to play the ambiguity card," he said.
What could a 'false flag' in Ukraine look like?
The US has been saying for some weeks that the Kremlin will attempt to stage some kind of attack as a pretext for a Ukraine invasion.
According to the Pentagon, Russian operatives will probably attack Russian land or ethnic Russians in Ukraine and film the incident and publicise the aftermath, as if it had been a Ukrainian attack on Russians.
“As part of this fake attack,” Pentagon spokesman John Kirby said on February 4, "we believe that Russia would produce a very graphic propaganda video which would include corpses and actors [who] would be depicting mourners and images of destroyed locations."
On Thursday, US Secretary of State Antony Blinken told a United Nations Security Council meeting there were many possible scenarios that Russia could create to justify an invasion.
"This could be a violent event that Russia will bring on Ukraine, or an outrageous accusation that Russia will level against the Ukrainian government," Mr Blinken said.
"Russia may describe this event as ethnic cleansing, or a genocide."
Dr Muraviev said it could also take the form of a large-scale hacking attack, endangering Russian lives, disguised as an attack by Ukrainian hackers.
He said that even the string of so-called "invasion dates" put forward by the West that have proved false could have been planted as part of a Russian "deception campaign".
A false-flag attack could be staged by any side, or real attacks could be portrayed as false flags to discredit the enemy. And, if done well, we may never know the truth.
"If you can point at the wrong side, it may have dire consequences given the current state of geopolitical tensions and the near war situation," he said.
