The ongoing military conflict between Armenia and Azerbaijan is prompting hundreds of Armenians living abroad -- as far away as Germany, Argentina and the United States -- to fly back and train as volunteers for the frontline.
This camp on a hillside above the Armenian capital, Yerevan, is run by a veteran of the last war over Nagorno-Karabakh, a disputed enclave, in the 1990s.
Since war broke out again last month, more than 1,000 people have been killed.
Aghasi Asatryan was in Germany, embarking on a career as an IT specialist. He immediately asked for a vacation, citing a family matter, and flew back to his hometown, Yerevan.
"I decided straight away that I will be here and that I will be defending my country if it needs me."
"My German employers wouldn't understand that a man would want to go to war."
Lessons include using hand grenades, repelling a gun attack -- though their guns are wooden replicas -- and rock-climbing, since Nagorno-Karabakh is mountainous.
It's controlled by ethnic Armenians -- and Armenia regards it as part of its historic homeland. The population there needs its protection, it says.
But it's internationally considered part of Azerbaijan, which considers the land to be illegally occupied.
"I know our history really well and I know that we, the Armenians, wouldn't have survived so many centuries without understanding that every man should fight for his homeland. We only could defend our homeland with blood and sweat and to survive through those centuries."
The school used to attract 20 to 30 people at a time to train for any renewed war -- now instructors say it's in the hundreds.
Armenia's defense ministry says about 10,000 people volunteered to take up arms on the first day of fighting.
Azerbaijan, too, has registered tens of thousands of volunteers, though its most recent numbers are classified.