The former Russian Prime Minister referred to the three Baltic states as "our" on Tuesday, adding Poland was "temporarily occupied".
Firebrand Russian politician Dmitry Medvedev said Tuesday that the Baltics belong to Russia.
Writing on Twitter, the former Russian Prime Minister referred to Lithuania, Latvia and Estonia as "our" provinces, saying they had "soiled themselves" over Russia's invasion of Ukraine.
The incendiary comments were made in response to remarks made by Emmanuel Macron last week that Moscow had "already lost geopolitically".
“De facto, it [Russia] has entered a form of subservience with regards to China and has lost its access to the Baltic, which was critical, because it prompted the decision by Sweden and Finland to join NATO,” the French President told the Opinion newspaper.
The three small Baltic States were occupied by the USSR until it collapsed in 1991. The Soviet Union is viewed negatively by large swathes of the population, who have embraced their future within the EU and NATO.
Worries have grown in the Baltics about the threat posed by Russia since it invaded Ukraine in February. They are vocal supporters of Ukraine, providing aid, arms and hosting significant populations of Ukrainian refugees.
Medvedev, who served as Russian PM between 2000 - 2004, has emerged as a virulent anti-West, pro-war voice within the Kremlin. His incendiary remarks often create controversy.
He also referred to Poland as "temporarily occupied", alluding to NATO presence inside the country, which includes 10,000 American troops, according to AP.
Though not directly in the USSR, Poland was a satellite state of the Soviet Union. The communist system, which was popularly perceived as corrupt and ineffectual, collapsed in 1989.
In response to Macron's comments, Medvedev wrote: "A geopolitical loss?"
"Now, all of the NATO member states go to bed at night, and wake up in the morning thinking of Russia. Moreover, some of the especially cowardly and suffering from phantom pains, like temporarily occupied Poland and our Baltic provinces, have well soiled themselves."
"So, if there has indeed been a loss, it is that of the primitive NATO politics, with its underlying ambition to play the exceptional role in the 21st century," he added.
One consequence of the Russian invasion is that it galvanised Sweden and Finland - historically closely aligned with NATO, but not full members - to launch bids to join the military alliance, boosting its size and power.
Helsinki was admitted in April, though Stockholm's membership has been delayed due to a political dispute with Turkey.
In his Twitter post, which has had more than one million views, Medvedev claimed Europe was acting as a vassal for the "perverted whims of Americans".
"In the process, it is hurting its own economy and ordinary Europeans with masochistic lust," he added.
The Ukraine war has fuelled high inflation across Europe, impacting food and energy prices especially.
In January, a Eurobarometer poll found that an overwhelming majority of EU citizens back the bloc's continued support for Ukraine.
Seventy-four per cent said "yes" when asked if they approved of the EU assisting Ukraine, with one-third saying they “strongly” approved. Yet, the numbers did vary considerably from country to country.