The Prime Minister does not believe the West will put troops on the ground to fight Islamic State in Iraq even though that would likely lead to defeating the group more quickly.
Some have suggested coalition forces need to do more to combat Islamic State.
But John Key said he agreed with US President Barack Obama, who he said rightly believed taking that action would create longer term difficulties in the region.
"I understand the frustrations but it's not just about winning the tactical short-term issues here with ISIL (Islamic State of Iraq and the Levant), it's about the long-term stability of the region."
Mr Key said New Zealand troops at Camp Taji were involved in just training Iraqi soldiers and that mandate would not change.