Biden paid homage to Poland’s long struggle for democracy in his speech that he delivered at the Royal Castle, which like most of Warsaw was destroyed by the occupying Nazi German forces during World War II and was later rebuilt.

He said Warsaw “holds a sacred place in the history of not only of Europe but humankind’s unending search for freedom. For generations Warsaw has stood where liberty has been challenged and liberty has prevailed.”

The American leader observed that democratic values “have always been under siege, they have always been embattled.”

“Every generation has had to defeat democracy’s moral foes,” Biden said.

Liberal critics of Duda and the government of Prime Minister Mateusz Morawiecki have been concerned that with the war in Ukraine, Poland’s rising importance as a key NATO country on the eastern flank could lead the United States and the EU to let up on the pressure on Warsaw over the rule of law.

Duda clearly preferred Biden’s predecessor, Donald Trump, and waited weeks after the U.S. election in 2020 to congratulate Biden.

But Russia’s invasion of Ukraine has prompted Duda and some other European populists to unite with Democrats in the United States and European leaders whom they had been in conflict with for years.

Since Russia invaded Ukraine, Poland has accepted the lion’s share of the more than 3.5 million Ukrainians who have fled. At the same time Poland is hosting some 10,000 U.S. troops, thousands of them arriving recently to help with the humanitarian crisis. Poland is also a base for sending military help into Ukraine, something that makes the country feel more vulnerable.

The Polish authorities were also in conflict with Washington last year over legal attempts to silence TVN, a broadcast network owned by the U.S. company Discovery Inc. The aim was to strip Discovery of its control of TVN, which produces independent news programs that are critical of the government.

Duda late last year vetoed the legislation, but concerns about press freedom remain due to the government’s use of public media as a party mouthpiece.

At the start of his speech Biden paid homage to two great Poles of modern history, John Paul II, the first Polish-born pope, and Solidarity leader Lech Walesa.

“While I know he couldn’t be here tonight, we’re all grateful in America and around the world to Lech Walesa,” Biden said, in a direct appeal to bridge the deep divides in Polish society.

Walesa is a harsh critic of Poland’s right-wing government and often accuses it of eroding the democracy that he helped to usher in.

Ruling party leader Jaroslaw Kaczynski and his allies have sought to significantly play down Walesa’s historic role in the successful fight against communism. They also accuse him of making too many compromises in the transition to democracy, something Walesa and others believe was necessary to prevent bloodshed then.