"To be blunt, I don't have any information, I don't know anything about that situation, I can't tell you what might happen in 10 years' time.
"But it's not our intention to put troops on the ground. Our intention is to continue to put troops on the ground."
Defence Minister Gerry Brownlee said today it was not worth speculating about ground troops until countries had a better understanding of the impact of the Paris attacks.
"We wouldn't speculate on anything like that until we have a proper discussion, but Paris does change a lot of things about the world we live in," he said.
New Zealand is of one more than 60 countries making some form of contribution to fighting ISIS in Syria and Iraq.
Mr Key said there was no doubt that the US-led coalition could "bowl over" ISIS very quickly.
But this approach failed to take into account the "delicate and finely balanced" politics in the Middle East.
"Ultimately you build another generation with a grievance against the coalition led by the US," he said.
He added: "It's not that [Obama] doesn't believe he can't defeat these people on day one, it's all the carnage you leave behind."
Mr Key noted that countries such as Iran felt the USA's previous interventions in Iraq had "made the situation worse".
The Prime Minister is in the Philippines to attend APEC trade talks. He said the fallout from the Paris disaster was likely to influence the talks, but the main focus was economic issues and the Trans Pacific Partnership.