WASHINGTON, Oct. 4 (UPI) -- Subways, rail systems and other transportation networks could be vulnerable to a German-based terrorist attack, officials warned the European community.
Washington followed the example set by its European counterparts and issued a travel alert for U.S. citizens traveling in Europe.
"Current information suggests that al-Qaida and affiliated organizations continue to plan terrorist attacks," a Sunday release from the U.S. State Department read.
Europe went on high-alert last week after a German citizen in custody in Afghanistan, Ahmed Sidiqi, told his interrogators of a plan to strike targets in Europe. Intelligence officials said drone missile strikes in Pakistan that killed a senior al-Qaida leader in September may have thwarted major plans.
Nevertheless, Washington said it was wary of terrorists plotting against the transportation infrastructure in the European community.
"U.S. citizens are reminded of the potential for terrorists to attack public transportation systems and other tourist infrastructure," the warning read.
Militants in Hamburg, Germany, are believed to be the responsible for the latest European terror alert, CNN International reports.
An al-Qaida cell from Hamburg led the team that carried out the Sept.11, 2001, attacks on the United States.
The British Foreign and Commonwealth Office added in its updated travel alert that "Germany has a high threat of terrorism."
Paris is already on high alert after declaring war on the North African branch of al-Qaida. French nationals were kidnapped by al-Qaida in the Islamic Maghreb in September.