WASHINGTON: President Barack Obama has thanked German Chancellor Angela Merkel for her country's "sacrifice" in keeping forces in Afghanistan, noting that she is being honored in Washington as the first German leader to address a joint meeting of the US Congress in more than 50 years.

Merkel, who was meeting with Obama before her appearance on Capitol Hill, said yesterday that she wanted to use the occasion at the White House and in her speech to Congress to express gratitude for American support "throughout the process leading up to German reunification."

Monday will be 20 years since the Berlin Wall was pulled down, leading to the reunificaiton of Germany that was divided among the victorious European allies at the end of World War II.