BERLIN -- U.S. diplomatic buildings in Germany have increased their security in response to a "heightened threat," and the U.S. Embassy warned Americans in the country to take precautions, officials said Friday.
German officials also said they have stepped up security outside U.S. bases, but left any specific danger unclear.
"U.S. diplomatic and consular facilities in Germany are increasing their security posture," an embassy e-mail announcement read. The message encouraged "Americans in Germany to increase their vigilance and take appropriate steps to bolster their own security."
The embassy refused to say if there was a specific threat, but urged Americans in Germany to "increase their vigilance and take appropriate steps to bolster their own personal security."
Interior Minister Wolfgang Schaeuble said German police have stepped up protective measures outside American bases, though a U.S. air force official said the military had not taken any additional measures of its own.
"We are taking these steps in response to a heightened threat situation," the embassy said.
In Washington, State Department spokesman Sean McCormack would not specify the nature of the threat but said the United States took it seriously enough review security at the Berlin embassy and U.S. missions in Bonn, Bremen, Dusseldorf, Frankfurt, Hamburg, Lepizig and Munich.
"It is serious enough and credible enough that we believed that we were obliged to put out the warden message warning Americans in Germany to be vigilant and exercise extra caution," he told reporters.
Germany's Interior Ministry said there were indications U.S. buildings in the country could be targeted, but refused to give details.
Germany has not experienced a major Islamist terrorist attack in recent years, but worries have risen since last July, when two suitcase bombs planted on passenger trains malfunctioned. Four suspects face trial in Lebanon. Additionally, the leaders of the Sept. 11 terror attacks were based for a time in Hamburg.
German federal police in March said Germany faces an increased threat of terrorism because its military takes part in missions in Afghanistan and elsewhere. German troops do not serve in Iraq, but German ships carry out anti-terrorist patrols off the Horn of Africa and German reconnaissance jets were recently sent to Afghanistan, where ground troops are stationed in the north of the country.
Thousands of U.S. servicemen and women are stationed with their families in Germany, which hosts key installations including Ramstein Air Base, Landstuhl Regional Medical Center and Grafenwoehr training center.
The U.S. military in Germany has not changed its security arrangements for the moment, said Air Force Maj. John Dorrian, a spokesman for the U.S. European Command in Stuttgart.