NYPD on High Alert Following Islamic State Threat

The New York Police Department has announced it is on high alert following calls on the behalf of the Islamic State for extremists to attack western countries.

New York's Police Commissioner Bill Bratton confirmed that the city's police force was on high alert Monday after a social media post by the Islamic State over the weekend that called for extremist sympathizers to commit terrorist attacks in western countries, including the U.S., Canada, Great Britain and France.

"There are a number of people who are in the process of being radicalized. Something like this can be the last straw to move them forward," Bratton told "CBS This Morning".

 "Additionally, they are continually working to attract new recruits," he added.

The call for more terror attacks comes after Islamic extremists attacked the headquarters of the Charlie Hedbo satire newspaper in Paris last Wednesday. Since the attack, a video was released showing one of the now-deceased suspects, Amedy Coulibaly, pledging allegiance to the Islamic State.

A memo sent out to NYPD officers and obtained by NBC New York also details the importance of extra vigilance this week.

"A least one officer must stand outside the vehicle at all times," the memo reads. "Pay attention to your surroundings, officers must pay close attention to approaching vehicles and anyone getting out of a vehicle. Pay close attention to people as they approach and look for their hands as they approach you."

In December, two police officers in New York were killed after a suspect, angry about the recent police-related deaths of two unarmed black men, shot the officers while they sat in their squad car in the borough of Brooklyn.