It’s likely the terrorists responsible for the Paris attacks had a way to communicate and plan their attacks that cannot be monitored by intelligence agencies.
Prime Minister John Key, who is in Vietnam on a trade mission, says that poses real challenges for our spies trying to monitoring those on New Zealand's terror watchlist.
The Paris attacks have exposed a gaping hole for intelligence agencies. In Vietnam today, John Key revealed for the first time just how much of a concern it is.
“The amount of dark communications, communication that are not monitored by our agencies - it is increasing,” he says.
Traditionally, intelligence agencies have been able to monitor things like phone calls and emails to foil terror attacks. But "dark communication" is the use of phone apps like Surespot and Wickr. They offer military grade secure messaging - and the messages then self-destruct, leaving absolutely no trace.
“What we've seen in recent times is that ISIL have become a lot more aware of where the capability to intercept information is, and where it isn't,” says Mr Key.
It appears some of the 40 New Zealanders on our terror watchlist are using dark communication apps, and spies can't get into them.
“The issue is this technology is very difficult to break into, essentially,” says Mr Key.
The discovery of a Syrian passport near the body of an attacker has increased fears that terrorists could be entering Europe by pretending to be refugees.
Seven hundred and fifty Syrian refugees are on the way to New Zealand, and Key says they are carefully checked.
“They go through a vetting process,” he says.
That includes a security check by SIS spies involving biometric testing and fingerprinting.
The information is then checked against databases held by the Five Eyes countries – the United States, the United Kingdom, Canada and Australia.
“We're part of the Five Eyes club, and that gives us an advantage over most other countries,” says Mr Key.
He has also revealed that, over the years, a small number of refugees wanting to come to New Zealand has been rejected – but he wouldn't say whether that was because of security concerns.
The Prime Minister leaves Vietnam tomorrow for the APEC forum in the Philippines, where world leaders will gather and talk of terror will dominate.