NEW YORK - The NYPD is on alert tonight but not increasing the number of officers on the streets following the discovery of an online graphic warning New York City of al-Qaida's return.

The stylized photo of the Manhattan skyline includes a caption in the Hollywood sign style that reads "Al-Qaeda" and "Coming Soon Again in New York."

According to Police Commissioner Raymond Kelly, the image comes from a militant propaganda website called Al-Ansar. He also said the NYPD does not believe the image is connected to a specific threat.

"The quality of the graphics is obviously pretty good, and that concerns us," Kelly said.

The police commissioner added that although the ad is disconcerting, it is not a reason to raise the terror alert in New York City.