Details are sketchy. But the city has taken some extra precautions against a radiological device being detonated by setting up checkpoints and employing sensors:

Vehicle checkpoints and other counterterrorism precautions are continuing in New York City Saturday morning. They're a response to what authorities are calling unsubstantiated online threats about a truck packed with radioactive material.

Police have been stopping cars and inspecting trucks in lower Manhattan and various other places around the city. They said they're also deploying extra radiological sensors on street, water and air patrols.

But federal, state and local officials are stressing that the threats haven't been verified. The city's terror alert status hasn't been changed. Deputy Police Commissioner Paul Browne says an Israeli Web site reported that online posts were made following a video released Sunday. It featured an American member of al-Qaida threatening foreign diplomats and embassies across the Islamic world.