“In referring to ‘a Polish death camp’ rather than ‘a Nazi death camp in German-occupied Poland,’ I inadvertently used a phrase that has caused many Poles anguish over the years and that Poland has rightly campaigned to eliminate from public discourse around the world,” Obama wrote. “I regret the error and agree that this moment is an opportunity to ensure that this and future generations know the truth.”

Polish President Bronislaw Komorowski made the letter, dated Thursday, available to journalists in Warsaw on Friday, expressing satisfaction at Obama’s words.

Komorowski called Obama’s letter “a very important moment in the battle for historical truth.”