NATO commander General David Petraeus says troops will need to remain in Afghanistan beyond the current date to transfer responsibility to Afghanistan's security forces in 2014.
New Zealand has more than 200 Defence Force personnel in Afghanistan working under NATO command and is due to decide whether to extend its mandate this year.
Withdrawal of the troops is currently planned to start in July.
General Petraeus told Radio New Zealand's Summer Report programme on Thursday he does not want to try to influence what the Government does about keeping its troops in Afghanistan and would not comment on whether New Zealand should recommit more soldiers.
General Petraeus has praised the head of the New Zealand SAS in Afghanistan as a great coach of an excellent team.
Lieutenant-Colonel Chris Parsons was recently recognised by the United States with its top honour for foreign officers - the Defence Meritorious Service Medal.
The award was made in recognition of what General Petraeus called his "outstanding command, leadership, and unwavering commitment to the mission".
General Petraeus told Summer Report the timing of the award was unconnected with an imminent decision by New Zealand on whether to extend its mandate in Afghanistan and was simply recognition of Lieutenant Colonel Parsons' achievements.