Thousands of protesters called Saturday for German troops to pull out of peacekeeping efforts in Afghanistan, while Chancellor Angela Merkel defended the nation's presence there as necessary to ensure security.

In her weekly video podcast, Merkel insisted that helping Afghans to rebuild their nation was the only way to keep the country from again becoming a breeding ground for terrorists.

"We have no alternative, because we can not leave Afghanistan to the hands of the terrorists," Merkel said.

"Since Sept. 11, 2001, we know that the security we defend in our own open, democratic countries must be defended in other countries where they lack sufficient governmental structures to do so themselves."

About 3,000 German troops are stationed mostly in the north of Afghanistan as part of the NATO-led peacekeeping efforts there.

Three separate mandates for Germany's involvement in Afghanistan are coming up for debate and renewal later this fall, and calls for an end to the mission have become louder, especially after authorities foiled alleged terrorist plots to bomb U.S. and other targets here earlier this month.

Some 5,000 peaceful demonstrators in downtown Berlin called for Germany to bring its troops home, insisting that efforts to help rebuild Afghanistan had failed short and that international efforts were doing more harm than good.