BERLIN — Tucked away in one of Germany’s finest wine regions close to the border with Luxembourg is the Büchel Air Base. Its perimeter is heavily guarded by the German Luftwaffe, or air force. And no wonder. Up to 20 nuclear weapons are stored in underground vaults, all in the custody of the 702nd Munitions Support Squadron, a U.S. Air Force unit, according to security experts.

No U.S., NATO or German Defense Ministry official will confirm or deny the existence of these weapons — at least not on the record — even though President Barack Obama has pledged to reduce and even rid the world of nuclear arms. “This issue is highly classified information,” said a U.S. diplomat. “We simply do not discuss it. You can ask questions and raise hypothetical scenarios, but I will circumvent them.”

But Germany’s new foreign minister, Guido Westerwelle, has taken a different view on the continuing presence of these weapons on German soil. In a bid to distinguish himself as quickly as possible in his new job, he called Saturday — the day Chancellor Angela Merkel clinched an accord with her new coalition partners, the Free Democrats — “for a country free of nuclear weapons.” But he refrained from saying where the weapons were located.

On the face of it, no issue could be better suited to Mr. Westerwelle who, as leader of the Free Democrats, has made this his foreign policy priority (and not Russia or Afghanistan). It is popular with a public staunchly opposed to nuclear weapons. All Mr. Westerwelle has to do, with support from Mrs. Merkel, is to ask the United States to remove the weapons when he visits the United States next month, days after Mrs. Merkel holds talks in Washington. And if Mr. Obama is true to his word, there is no reason why the United States could not take them out, as it has quietly done over the past few years from other locations in Germany and other West European countries belonging to NATO, according to German defense experts.