A nice history angle is provided by the US State Department “share” service in an official embassy post about Russian false flag operations.

Russia’s false flag operations date back decades and take many forms. In 1939, the Soviet Union shelled its own troops outside the Soviet village of Mainila near Finland. It then blamed Finland for the attack and invaded its neighbor in violation of the two countries’ nonaggression pact.

Then they jump ahead to five years ago.

More recently, Russian state hackers have disguised themselves as operatives of Iran’s regime or the Islamic State of Iraq and Syria (ISIS) to evade responsibility. In 2017, Russia’s military launched a ransomware attack against Ukrainian businesses. While the attack was disguised to look like the work of profiteers rather than state actors, a joint investigation by Australia, Canada, New Zealand, the United Kingdom and the United States found the Kremlin responsible, according to Wired magazine.

The link to the Wired article is very important because there you will find motive.

[James Lewis, the director of the Strategic Technologies Program at the Center for Strategic and International Studies] argues that Russia’s ultimate goal with its false flag attacks, aside from creating confusion and deniability, is to make the case that attribution isn’t truly possible—that when a US intelligence agency or Department of Justice points the finger at the Kremlin after hacking incidents, they’re merely guessing. “They don’t like being indicted,” he adds. “They would like to create a counter-narrative: ‘You can’t trust the Americans. Look, they got this wrong.'”

Those who try saying that attribution of attack is not possible — sowing doubt about science and intelligence — are feeding into the Russian military intelligence narrative meant to enable their sloppy and inexpensive attacks.

Historians might be the first to disagree with Russia on this. I mean who really disputes today whether Russian relations with the Confederation of Targowica (noble league backed by Russian Empress Catherine II to oppose the Polish Constitution) is what led to Poland being invaded 16 May 1792 (without Russia even declaring war), which resulted in the Russo-Prussian Second Partition? And what about 28 June 1788 when Sweden’s King Gustavus III declared war on Russia by disguising his own soldiers in Puumala with Russian uniforms?

Related: The unCERTainty of attribution.