British counter-terrorism officers are on high alert amid fears of copycat attacks following the New Orleans New Year’s Day and Magdeburg Christmas market tragedies.

Authorities are concerned that Islamic State supporters could be provoked to launch terrorist attacks, including knife and vehicle assaults, after two recent major attacks in the West with alleged ties to Islamic extremism.

A spokesperson for UK Counter Terrorism Police said Thursday that officers “continually assess international events” to understand if there are any implications for national security.

Britain is high on the terrorist target list, with more than 600 live MI5 investigations into possible plots and over 3,000 suspected extremists.

The threat of international terrorism in the UK is considered “substantial” as an attack is “likely” and armed police are patrolling iconic sites that could be targeted.

“We already have hostile vehicle measures in place in many locations but you have to ask yourself how much do you want to do, it’s not possible to protect everywhere, however iconic sites should pay attention to the threat. It’s always a delicate balance between security, safety and our freedoms. There are so many streets in the UK that you would call iconic.”

“It’s impossible to protect them all from someone who can just jump into a car and drive at the public. Intelligence is the only real way to stop an attack like this, before they get into the vehicle.”

William Wechsler, former U.S. deputy assistant secretary of defense, said Thursday that the rise of an Islamic State-aligned HTS in Syria has been seen by extremist sympathizers as a “harbinger of great victory.”

He said, “Just a few years ago there was an attack in New York City inspired by the Islamic State the same year there was an attack in London… so the threat of Islamic State directed and inspired violence has not gone away, in fact it may be increasingly directed in part by some of the news that comes out of the region where Islamic State is most active.

“There’s an ideology behind the Islamic State of the recreation of the caliphate that many who share that particular vision for Islam find very attractive. When they see terrorists and others that subscribe to that vision be successful in places like Syria that further indicates in their minds their religious mission and might inspire them towards attacks elsewhere as well.”