New Zealand has garnered international headlines for not following other countries that are expelling Russian diplomats in protest over the use of a Russian nerve agent to poison former double agent Sergei Skripal and his daughter Yulia Skripal.
Twenty six countries have reportedly expelled Russian envoys in the past few days, among them New Zealand's Five Eyes security partners Australia, Canada, the United States and the United Kingdom.
It comes after the UK's initial move to boot out 23 diplomats – a move that was matched by Russia.
Ardern said New Zealand was in step with its security partners on the issue.
"We've gone through the SIS to ensure we don't have any of those present in New Zealand. If we did, they would be expelled in the same way our partners have."
But security analyst Paul Buchanan said Ardern's statement about Russian spies was laughable.
"Unbelievably silly thing to say, and it has made New Zealand a laughing stock," he told Radio NZ this morning.
He said not all of those who were expelled were undeclared spies.
"This was a symbolic gesture. This will reduce Russian intelligence collection capabilities in the targeted countries, but this is mostly about repudiating Russia's actions abroad.
"Certainly the [Russian] Embassy has intelligence officials. They are known to the New Zealand authorities, and those are exactly the people that are being expelled in other countries."
The Ministry of Foreign Affairs website lists 17 diplomats and staff in the Russian Embassy based in Wellington, including Ambassador Valery Tereshchenko.
Buchanan said Ardern's comments would not compromise the daily intelligence sharing with other Five Eyes nations, but he expected that the Government would "wind up having to hastily expel somebody, just to keep up appearances".
He said Ardern's statement could hurt New Zealand's international image, following Foreign Minister Winston Peters' previous comments in which he appeared to take a soft stance on Russia.
He noted that Peters has questioned Russia's involvement in the shooting down of flight MH17 over the Ukraine in 2014, whether it had meddled in the US election, and Peters' initial reluctance to name Russia as the prime suspect in the nerve agent attack.
"This is very odd stuff for Winston Peters to say," Buchanan said.
"Although there's been some backtracking, that's going to be the backdrop to the questioning in international capital about where New Zealand stands."
Ardern has defended Peters' response to the nerve agent attack, saying he condemned it immediately and called it repugnant.
After the poison attack, Ardern said New Zealand would no longer restart free trade talks with Russia - a promise that Labour and New Zealand First had agreed to in their coalition deal.
