[EEGator]

What flag is that?

[Liaison]

Donetsk People’s Republic , supposedly. One of the 2014 breakaway states the Russians carved out of Ukraine.

[Vlad0]

That is the flag of one of the two break-away Republics in Eastern Ukraine, the Donetsk Peoples Republic:

Wikipedia article: Donetsk People's Republic.

You may remember that a few days before the Russians invaded Ukraine that President Putin recognized the two break-away states (the other being the Luhansk People's Republic) as a prelude to the invasion.

Here's the flag of the Donetsk People's Republic, per Wikipedia:

Map of the territory controlled and claimed by the DPR:

I believe Mariupol is the light green dot surrounded by dark green, on the Black Sea, towards the bottom of the map.

[Who is John Galt?]

What flag is that?

Apparently it is associated with the Donetsk People's Republic...

;>)

[Navy Patriot]

Just speculation, it might be the Russian Flag used for this particular Military Campaign to distinguish it from the standard Russian Federation tricolor.

[Eleutheria5]

Pro-Russia separatist militia.