The New York Police Department (NYPD) announced Monday that they are currently on heightened alert as ISIS threats last September 2014 resurfaced. During the weekend, a video was released by the Islamic State threatening military and law-enforcement personnel in the U.S., France, Australia and Canada.

The said video was re-released by the ISIS on Twitter threatening the NYPD and other defense forces. According to the Wall Street Journal, ISIS spokesperson Abu Muhammad al-Adnani said the threats were made specifically to security and intelligence members, the police, soldiers, patrons, troops as well as civilians. It also encourages extremists to rise up and kill the police, Yahoo! News quoted.

"Do not let the battle pass you by wherever you may be," al-Adnani said. "Strike their police, security and intelligence members, as well as their treacherous agents."

Al-Adnani also called for lone attacks, the New York Daily News reported.

"[For those] who don't have an improvised explosive device or a bullet, [you] can smash his head with a rock, or slaughter him with a knife, or run him over with your car," al-Adnani added.

As stated on the internal memo, CNN revealed the NYPD employees were informed to stay alert and consider tactics at all times while on patrol. Across the nation, the Federal Bureau of Investigation (FBI) and the U.S. Department of Homeland Security have also issued the same bulletin because of the ISIS threats.

"As you may recall, there was a similar threat, a Twitter threat, back in September, and shortly thereafter there were a number of attacks in Canada, Australia, also an attack here -- an ax-wielding individual attacked four of our officers," NYPD Commissioner William Bratton on "CBS This Morning" on Monday.

"We take these threats very seriously," Bratton added. "It's something we continually try to drive home to our officers: This is real, that we need to be constantly vigilant."

Aside from the NYPD, Sergeants Benevolent Association members have also been instructed in an email about the ISIS threats.

"If you are assigned to a fixed post, do not sit together in the RMP [police car]," the e-mail obtained by The New York Post said. "At least one officer must stand outside the vehicle at all times. Pay attention to your surroundings. Officers must pay close attention to approaching vehicles . . . Pay close attention to people as they approach. Look for their hands."

The heightened alert on the NYPD and other defense forces came after the release of the ISIS video threat on weekend and the Paris attacks last week that killed 15 civilians and two police officers.