Although he felt no immediate threat to Latvia, the "atrocities" in Ukraine mean "what I'm doing right now could matter in the future", he said.
"Many of us have pacifist tendencies. We took arms and started learning to shoot because we want to be able to protect our loved ones," he told AFP.
After basic training, he will take part in a specialised course to improve communication between civilians and troops.
Others who wish can also specialise in areas such as anti-tank warfare, medical aid or train to become snipers.
"My wife said at least one family member needs to join and get some basic skills," said 35-year-old entrepreneur and father-of-two Juris Kukulis.
"So if something happens, we know what to do."
