Farmers, shopkeepers, police officers and a mayor have volunteered to play "bad guys" in a large-scale realistic war game.
The military exercise, involving 2200 personnel from 10 countries including crack US Marines, is being played out in South Canterbury towns, ports, and farms.
Backroom staff at the New Zealand Defence Force have spent months concocting Exercise Southern Katipo 2013 - a scenario where the lower half of the South Island is a made-up Pacific nation called Mainlandia.
After 29 members of the 'Mainlandia Defence Force' were killed in a supposed 'training accident' in 2010, ethnic tension has erupted between the imagined 'Bekaran' and 'Alpirian' regions.
Peace talks failed and now a New Zealand-led task force has been sent to the region, arriving by air and sea, in Timaru - the centre of the Bekara region.
The soldiers, sailors, and airmen have been told to restore law and order.
Today, ominously-grey warships sat in Timaru harbour and giant US Air Force C-17 Globemasters sat on the tarmac at the local airport, where the entrance was blocked by a heavily-fortified checkpoint, manned by a high-calibre machinegun.
Quiet streets, backroads and fields of South Canterbury were swarming with camouflaged, armed soldiers on fake patrols.
And the local population has been enlisted to play their part and bring as much realism to the exercise - billed as New Zealand's biggest ever international military exercise - as possible.
While it's the stuff of fantasy, it closely mirrors situations which have occurred in overseas conflicts in recent times.
Commander of the coalition forces on exercise, Colonel John Howard said some farmers had "agreed to play the bad guy", and would provide access to their land, outhouses, and buildings, while giving "cover stories for their nasty business".
"It's role playing, like kids do in the backyard at weekends, only a little bigger," he said.
"The good guys will come looking, so it'll bring another dimension to their Saturday or Sunday.
"We'll be in and around town doing a range of activities... engaging with the local community. It will be a real experience."
The mixture of maritime and alpine terrain, set amongst a small population, made South Canterbury an ideal location, Colonel Howard said.
Timaru District mayor Damon Odey is one of many civilians taking part in the role playing.
He'll be playing himself as mayor of the local populace, and the figure in charge of the strategically critical port.
Army officers will be grilling him, and he's looking forward to the different challenge - like most civilians who've volunteered to be involved, he says.
"We roll pretty easily here," Mr Odey said.
"In the North Island, and in the bigger centres, it'd be much harder to put something like this together.
"But in a smaller area like South Canterbury, we can see the benefits of being involved and making it happen."
To be training amongst the civilian population was "extremely unique", according to Lt. Col Patrick Aspland, commander of a US Army task group involved in the exercise.
"In the US Army, we typically do exercises in a training area isolated from the local population, replicating the local population with role players," he said.
The US Army was looking forward to working alongside Kiwis, Tongans and Papua New Guineans, and seeing how they operate in the field.
Other nations involved in the joint exercise include Australia, Canada, France, Malaysia, Singapore and the UK.
Interacting with the public, and being so visible, the Defence Force hopes the exercise - which will run until November 29 - will prompt the public into asking questions about what it means to New Zealand, and also act as a recruitment tool.
The Defence Force says the exercise will test its capability to mount a medium-scale operation that involves maritime, land and air assets.
And given the level of operations overseas over the last decade, especially in Iraq and Afghanistan, it will give the Defence Force a chance to "reevaluate how we do things," said Col. Howard.