US Secretary of State Hillary Clinton has said the US will donate $15m (£10m) to preserve the site of the Nazi death camp at Auschwitz-Birkenau.
Mrs Clinton was on a visit to Poland, where she oversaw the signing of a key missile base agreement.
She warned of a "steel vice" of repression crushing democracy and civil liberties activists in countries such as Iran, Egypt and Zimbabwe.
She held up Poland, which elects a new leader on Sunday, as a model democracy.
More than a million people, most of them Jews, were murdered by the Nazis at Auschwitz during World War II.
The money to preserve Auschwitz-Birkenau depends on Congressional approval.
Mrs Clinton defended US funding for advocacy groups in other countries, which some governments condemn as meddling.
Mrs Clinton said social activists in many countries were being harassed, censored, arrested or killed.
The Iron Curtain no longer existed, she said, "but we must be wary of the steel vice in which governments around the world are slowly crushing civil society and the human spirit".
Mrs Clinton later travelled on to Azerbaijan, and is also due to visit Armenia and Georgia.
The secretary of state witnessed the signing of the amendment to the ballistic missile agreement with her Polish counterpart, Radoslaw Sikorski, in the southern city of Krakow.
The deal sets up a permanent US missile base as part of a revamped version of the controversial missile defence shield.
Russia opposes a Polish base hosting US missiles. Mrs Clinton said the new deal did not threaten Russia.
Mrs Clinton said the agreement would "protect Poland and our allies from evolving threats, such as those from Iran".
In Azerbaijan and Armenia, Mrs Clinton will push for a resolution of the region's conflicts and will seek to bolster US access to an overland route used for supplying troops to Afghanistan, says the BBC's David Stern in Kiev.
In Georgia, Mrs Clinton will have to reassure officials that the government of embattled President Mikhail Saakashvili still has US support despite Washington's attempt to improve relations with Russia, our correspondent adds.