WASHINGTON (AP) — With help from the U.S., the Czech Republic has eliminated its stockpile of highly enriched uranium, becoming the 10th country to remove all such material since President Barack Obama began pushing to rid the world of nuclear weapons, the White House said Friday.

The announcement came on the fourth anniversary of a speech Obama delivered in the Czech capital of Prague shortly after taking office in 2009. He declared nuclear terrorism the world’s greatest threat and called on other countries to secure their stockpiles of nuclear material.