By Louis Charbonneau

BERLIN, Sept 6 (Reuters) - The suspected car bomb plot uncovered in Germany this week underlines the importance of Germany and other NATO allies keeping troops in Afghanistan, a senior U.S. diplomat said on Thursday.

Germany arrested two German converts to Islam and a Turk on Tuesday who were suspected of being on the verge of launching major bomb attacks.

Some Germans fear Berlin's decision to participate in the NATO peacekeeping mission in Afghanistan after the Sept. 11, 2001 attacks on the United States is one of the main reasons their country appears to have been targeted.

But Richard Boucher, U.S. Assistant Secretary of State for south and central Asia, said Germany's involvement had not increased the threat of attacks.

"These plots are out there. We've seen them hit New York and London and Madrid and now we're uncovering a plot in Germany," he told Reuters during a visit to meet German government officials.

"It's all the more important that we ... keep in Afghanistan where we're working to keep terrorism from coming out of that part of the world."

Boucher said the United States would one day capture Osama bin Laden, the prime target of the U.S.-led invasion of Afghanistan.

"It's still important to get him," Boucher said. "He's still part of the command apparatus of the Taliban and al Qaeda. They're out there. He's somewhere in that region."

"ENDURING FREEDOM"

Germany is debating whether to renew its Afghan peacekeeping mandate. Opinion polls show most Germans would like the troops brought home, but the government has recommended renewing its entire Afghan mandate and stepping up reconstruction work.

The recommendation requires parliamentary approval and many lawmakers want to drop at least part of the Afghan mandate.

Some parliamentarians from the Social Democrats (SPD), which govern in a coalition with Chancellor Angela Merkel's conservatives, have demanded that Germany drop its mandate to participate in the U.S.-led Operation Enduring Freedom (OEF).

German analysts say Germans see OEF operations against the resurgent Taliban as the main cause of civilian casualties in Afghanistan.

Boucher said the message from Washington was that all elements of the NATO mission -- military, reconstruction and training of Afghan forces -- were crucial.

"To the extent that any ally, any country can be involved, we like them to be involved in more rather than less," he said.

Boucher said he found the negative attitude of some Germans towards OEF surprising since it was mostly a training mission.

He also made clear Washington hoped Berlin would extend its mandate beyond the stable north so that it can send troops to the south where the Taliban insurgency is focused.

So far Berlin has refused to deploy troops in the south. Reuters issued a statement on Thursday advising its global client base of the suspension.

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