"Go, go!" shouts a soldier at five Red Cross aid workers crammed into a 4x4 truck speeding into the woods as explosions go off nearby, sending up plumes of white smoke.
The scene feels menacing and real. But it is in fact taking place far from an actual battlefield and just a stone's throw from a city renowned for its international peace efforts, in one of the safest countries on the planet.
Welcome to Alpesia, an imaginary land created by the International Committee of the Red Cross (ICRC) 15 years ago in the woods of Geneva. Here the Sequane Liberation Front rebels are facing off against the authorities in a "conflict" tailored to teach new aid workers how to face the increasingly dangerous world they will soon be ushered into.
Nearly 200 participants, who have to be between 25 and 35 years old, pass the simulation test each year before joining a profession where armed attacks, kidnappings and hospital bombings are becoming ever more prevalent.
In the Swiss woods, they get a taste for what life could be like on mission: military checkpoints, visits to destroyed hospitals and a refugee camp -- all within eight days of practical and theoretical training.
Split into groups of five, the new International Committee of the Red Cross (ICRC) delegates drive into the forest in 4x4s en route for a refugee camp. But before long they are stopped at a checkpoint.
Some of the aid workers are separated from the group by a soldier who keeps them in check with a real -- though hopefully not loaded -- assault rifle.
Now it is up to the aid workers to talk their way out of the situation and demonstrate they can keep calm, pick their words carefully and convincingly explain their neutrality and their mission.
"Sometimes, fake ICRC soldiers take it up a notch if they are not satisfied with the behaviour of the new delegates," spokesman Philippe Marc Stoll tells AFP.
After the roleplay, the debriefing is harsh.
Today, "soldier" Benjamin Eckstein chastises the group for allowing an armed soldier to get into their vehicle, effectively turning it into a "legitimate military target".
"The simulation on the ground was really realistic," enthuses 29-year-old Italian Gaia Pallechi, who is being sent to work in Bogota.
The training makes it possible to correct mistakes and "avoid them on the ground", says Moroccan Nezar Tamine, 26, who has already begun a stint in Beirut but is in Geneva getting the skills he needs.
-- Once accidentally caught in crossfire, now a target --
But even the best of hostile environment training cannot avert all dangers.
Last year "was the most difficult year for the ICRC in security terms since 2003 and 2005", the organisation's chief Peter Maurer told reporters last month.
In Syria, 20 local Red Crescent workers have been killed since the bloody conflict began in March 2011.
Humanitarian groups are facing ever more difficult conditions as conflicts, like the one in Syria, stretch on for longer and longer.
In 2011, a record 308 humanitarian workers around the world were killed, kidnapped or wounded, according to the latest available statistics from Humanitarian Outcomes, a US-based group whose data is used by the UN.
Most attacks took place in a small number of countries: Afghanistan, Pakistan, Somalia, South Sudan, and Sudan.
Kidnappings especially have been on the rise: in 2012, 87 humanitarian workers were kidnapped worldwide, compared to just 24 in 2002, according to Humanitarian Outcomes.
"If you look back 10, 20 years, we have moved from being caught in the crossfire, which was purely incidental, to being... really targeted," Amin Awad, emergency security chief at the UN refugee agency UNHCR, tells AFP.
UNHCR workers preparing to go out into the field are also subjected to mock hostage takings, kidnappings and other stress situations -- and also in some of the world's most peaceful spots, in Germany, Sweden and Norway.
"The humanitarian space is shrinking, the environment where we work is becoming increasingly insecure, and staff have to be prepared for the worst," Awad says.
The UN provides basic training for everyone going out on a mission, and for the past five years has also been offering more specific training for each conflict zone, says Jens Laerke, spokesman for the world body's humanitarian affairs agency.
The training programme "has been professionalised a lot in the past four to five years, but it's still a work in progress", he says.
According to Laerke, the humanitarian profession is basically suffering from its popularity, as there are probably 10 times more aid workers in the field today than a decade ago.
"There are a lot more organisations, more people out there going into a lot more places, so obviously more get kidnapped and killed, unfortunately," he explains.
Philippe Ruscassier, who heads training for Doctors Without Borders (MSF) in France, agreed, pointing out that "when you have 10,000 NGOs, people no longer know" who you are, which can cause problems for workers with neutral NGOs like MSF and the Red Cross, who may get confused with more partisan organisations.
As he prepares to go back into such a reality in Beirut, Tamine says the ICRC training is important.
"It is really good to have an idea of how to act to stay safe," he says.