Just days after the United States said it would increase troop numbers in Afghanistan and ask its allies to do the same, New Zealand on Friday announced an extra three non-combat military personnel, boosting its military commitment to 13.

US President Donald Trump on Monday unveiled his strategy to end the conflict in Afghanistan, committing the United States to an open-ended conflict and signalling he would dispatch more troops to America's longest war.

US officials have said Trump had signed off on plans to send about 4,000 more US troops to add to the roughly 8,400 now deployed in Afghanistan. US. Defence Secretary James Mattis has since said exact troop numbers are yet to be decided.

Trump said he would ask coalition allies to support his new strategy, with additional troops and funding, to end the 16-year conflict.

New Zealand Defence Minister Mark Mitchell's announcement boosting the country's Kabul-based troops to 13 follows a request for NATO (National Atlantic Treaty Organization) to send more troops to Afghanistan earlier this year.

New Zealand has had troops in Afghanistan since 2001. Its presence has been decreasing since 2013 but it has kept some personnel on the ground to train local officers.

"New Zealand will continue to stand alongside our partners in supporting stability in Afghanistan and countering the threat of international terrorism," said Mitchell.