Former Russian President Dmitry Medvedev has taken aim at Poland in an astonishing attack.
Mr Medvedev appeared to suggest US President Joe Biden has "clear signs" of "senile insanity" and warned Poland that it would suffer for its decision to sever economic ties with Moscow.
The now deputy chairman of the Russian security council branded Poland a "community of political idiots".
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Poland's Prime Minister, Mateusz Morawiecki, is to welcome the US President later this week as Western leaders respond to Vladimir Putin's illegal invasion of Ukraine.
In a letter published on Telegram, Medvedev fumed: "The interests of the citizens of Poland have been sacrificed due to Russophobia of 'mediocre politicians' and their 'puppeteers from across the ocean' with clear signs of senile insanity."
Putin loyalist Medvedev, who was president between 2008 and 2012, and Prime Minister between 2012 and 2020, warned that cutting economic ties with Russia would have dire consequences for Poland.
He continued: "The decision to abandon the purchase of Russian gas, oil and coal, the opposition to Nord Stream 2 have already caused serious damage to the economy of this country. Now it will only get worse."
Mr Medvedev claimed Poland's elites were determined to swear allegiance to their "overlord".
Mr Biden is due to travel to Europe this week for meetings with allies to discuss further sanctions on Russia.
Ahead of the trip, he discussed Russia's "brutal" tactics in a call with European leaders, the White House said.
Russia's siege and bombardment of Mariupol, which European Union foreign policy chief Josep Borrell called "a massive war crime", is increasing pressure for action.
Biden said Putin's "back is against the wall and now he's talking about new false flags he's setting up including, asserting that we in America have biological as well as chemical weapons in Europe, simply not true".
He continued: "They are also suggesting that Ukraine has biological and chemical weapons in Ukraine. That's a clear sign he's considering using both of those."
Biden also told businesses to be alert for possible cyber attacks by Russia.
"It's part of Russia's playbook," he said in a statement.
Medvedev's letter in full
About Poland.
While Europe is painfully aware of the damage that anti-Russian sanctions will inflict on it, our most beloved European country, as always, ran ahead of the speeding steam locomotive. Literally.
Prime Minister Mateusz Morawiecki, together with Deputy Prime Minister Kaczynski, as well as the prime ministers of the Czech Republic and Slovenia, travelled to Kyiv on a specially guarded train. Almost like Ilyich in an armoured car with German money.
We talked with Zelensky, promised friendship and help. They lied, of course. Returning, Morawiecki solemnly announced the development of a program for "de-Russification of the Polish and European economy." Courageously specifying that "this may be costly."
Absolutely and completely right: expensive and pointless. But Poland can no longer take into account the costs. Everything that she could lose because of her own long-term pathological Russophobia has already been lost. So now, as the beloved neighbors of the Poles say, "the shed burned down - burn down the hut."
When it comes to Russia, Poland literally writhes from "phantom pains." It is very difficult for its elites to come to terms with the fact that the Time of Troubles almost 400 years ago ended with the expulsion of the Polish occupiers from the Kremlin. That the great empire of the Commonwealth did not take place later. And the reason for this is not the intrigues of Russia, but internal squabbles, corruption, economic failures, lost battles. And so - for many centuries.
Polish propaganda is the most vicious, vulgar and shrill critic of Russia. Community of political imbeciles.
Despite the fact that in our country it is not customary to hush up even the darkest pages of our common history, in Poland they dream of forgetting about the times of the Second World War. First of all, about those Soviet soldiers who defeated fascism, expelled the invaders from Polish cities and did not let them blow up Krakow, liberated the prisoners of Auschwitz and Majdanek.
History is now being redrawn, monuments are being demolished. But the fascist occupation is openly equated with the "Soviet". It is difficult to come up with a more deceitful and disgusting rhetoric, but the Poles succeed.
At the same time, there are no anti-Polish sentiments in Russia and never have been. Sociologists testify that the citizens of our country are quite friendly towards this people. It is impossible to forget the outburst of sympathy and compassion caused by the plane crash near Smolensk, when a high-ranking delegation led by the president died. People carried flowers to the embassy and churches, expressed condolences in the press and social networks. In Russia, I, as the head of state of the country, declared a day of mourning.
Later, during my visits to Poland, I became convinced that our countries have no obstacles to improving relations, this is a road with oncoming traffic. However, the political elites, led by the PiS party of Kaczynski No. 2, controlled by the American masters, did everything to block the normal path.
Now the interests of the citizens of Poland have been sacrificed to the Russophobia of these mediocre politicians and their puppeteers from across the ocean with clear signs of senile insanity. The decision to abandon the purchase of Russian gas, oil and coal, the opposition to Nord Stream 2 have already caused serious damage to the economy of this country. Now it will only get worse. The same applies to many other steps, which are based not on the economy, but on politicking under the guise of "de-Russification". But now it is much more important for the vassal Polish elites to swear allegiance to their overlord - America than to help their own citizens, so they will constantly keep the fire of hatred for the enemy represented by Russia.
What will citizens gain from this? Absolutely nothing.
But sooner or later they will understand that hatred of Russia does not strengthen the society, it does not contribute to well-being and tranquility.
And vice versa: economic cooperation with our country is beneficial for the Poles, human ties are indispensable, and cultural and scientific exchange between the birthplaces of Pushkin and Mickiewicz, Tchaikovsky and Chopin, Lomonosov and Copernicus is vital. And most likely, then they will make the right choice - on their own, without prompting and pressure from overseas elites suffering from dementia.
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