The New Zealand Defence Force tried unsuccessfully to borrow mine-resistant vehicles from the United States military to protect troops from roadside bombs in Afghanistan.
The Humvee vehicle in which three New Zealand soldiers were killed on Sunday was vulnerable to insurgent bombs and the US military has stopped using them.
Defence Force officials said New Zealand's Provincial Reconstruction Team in Bamiyan had the best available equipment for the province's difficult terrain, and that no vehicle would have survived the 20kg bomb which killed the soldiers.
But New Zealand armed forces did try to upgrade its vehicle fleet two years ago by adding a mine-resistant, all-terrain vehicle, or M-ATV.
Asked whether New Zealand armed forces would again seek mine-resistant vehicles after the deaths, Defence Minister Jonathan Coleman said yesterday: "The advice we've got is that our vehicles are what's needed to do the job.
"Heavier vehicle types wouldn't be able to cope with all the roads; that's why our guys use that mix of LAVs (light-armoured vehicles) and Humvees."
New Zealand borrowed its Humvees from the Americans, who now use mine-resistant vehicles.
Former Chief of Army Major-General Louis Gardiner said mine-resistant vehicles were difficult to get hold of because they were in demand for the US armed forces.
But the vehicles might not be suited to some roads.
"The roads are narrow and steep, and you're continually running into vehicles coming the other way.
"The last thing we need when you're trying to win the hearts and minds is stop the Afghans going about their business."
The US vehicles were 50cm wider than a Humvee, and four times heavier.
The Defence Force bought 105 light-armoured vehicles in 2001, but it would not say yesterday how many of them were in Afghanistan.
Previous reports showed three LAVs were sent to the country in 2009 and another eight last year.
The Canadian-designed LAVs have been upgraded for protection against explosives since they were bought, but were still vulnerable to bombs of the sort which killed the three soldiers.
United States troops who used a similar vehicle in Afghanistan nicknamed them "Kevlar coffins".