Intelligence Signals New Terrorist Threats

The Homeland Security Department warned law enforcement officials that Al Qaeda may be plotting to fly cargo planes from outside the country into such crucial targets in the United States as nuclear plants, bridges or dams. A department official said the information came from a single source overseas and had not been corroborated.

Separately, the U.S. Embassy in Saudi Arabia said it would close its diplomatic missions there for an undetermined period because of credible information about impending terrorist attacks.