Authorities briefly closed part of Penn Station on Friday and commuters headed to work under the watchful eyes of police after a newly disclosed terror threat against the New York subway system.

A discarded soda bottle filled with an unidentified green liquid was found at the station during morning rush hour, Amtrak officials said. The substance did not pose a threat to passengers and was removed for testing....

--AP

Better safe than sorry, I suppose, but if they're going to shut down parts of the transit system every time they find something like this, there are going to be a lot of shutdowns.

Although usually what's in such discarded bottles is an unidentified yellow liquid....