Lech Walesa, the former Polish president and Solidarity trade union leader who played a leading role in the fall of Communism, signed a letter to President Donald Trump expressing "horror" at his argument with Ukraine's Volodymyr Zelenskyy.
The Nobel Peace Prize-winner posted the text of the letter, which was signed by 39 Polish former political prisoners, on Facebook on Monday.
In an extraordinary meeting that was broadcast live on Friday, Trump accused Zelenskyy of being ungrateful for U.S. aid, of showing disrespect to his country and of risking World War III, casting into doubt Washington's ongoing support for Ukraine in its three-year-long war with Russia.
"We watched your conversation with the President of Ukraine Volodymyr Zelenskyy with horror and distaste," the letter said.
"We consider your expectations regarding showing respect and gratitude for the material assistance provided by the United States to Ukraine in its fight with Russia to be offensive," the letter continued.
"Gratitude is due to the heroic Ukrainian soldiers who shed blood in defence of the values of the free world."