Islamic State says the two people who massacred 14 people in a San Bernardino mass shooting were supporters. They made the declaration in an online radio broadcast, three days after the attack in Southern California.
Otago University international relations expert Robert Patman joined Paul Henry to discuss the issue.
Mr Patman says it shows how vulnerable the United States is to this type of terrorism.
He says that with the country having more than 300 million guns there is no shortage of people that ISIS can target as recruits.
"That's the big difference between the United States and a country like New Zealand. There will be ISIS sympathisers here but their access to guns will be much less easy than it is in the United States."
Mr Patman says that there needs to be a multi-pronged approach to combating ISIS.
The west needs to engage in air strikes and possibly needs to put troops on the ground.
"It also is a political struggle. We have to have a powerful counter-narrative, both within the Islamic world and within the western world. We shouldn't be defensive about the virtues of freedom and democracy."
Watch the video for the full interview.