Going to fight in another country's war requires an 'absolutely pathological drive' to succeed, says a former international volunteer

• Ukraine is accepting international fighters to help combat the Russian invasion.
• Stefan Bertram Lee, a UK resident who volunteered to fight against ISIS in Syria, says international fighters need to be committed to the cause.

A UK citizen who volunteered to fight in Syria's civil war has some advice for all the foreign fighters going to Ukraine: You can't half-ass it.

"If you're not 100% behind it, don't do it. You need this absolutely pathological drive within you and stubbornness to kind of get you there, to get you through it, and so on," Stefan Bertram-Lee told Insider. "If you're at all unsure the tiniest bit, don't do it, because you'll probably just give up somewhere along the way."

In February, after Russian President Vladimir Putin sent troops into Ukraine, Ukrainian Prime Minister Volodymyr Zelenskyy called for international reinforcements. Since then, thousands of people across Europe have headed to Ukraine, or pledged to go there, to fight off the invasion and offer humanitarian aid. Some battalions in Ukraine's military have already accepted foreign fighters, and Zelenskyy announced the formation of an international legion as well. The Ukrainian government said that around 20,000 people have volunteered so far.

Bertram-Lee, who identifies as nonbinary, also volunteered to be a foreign fighter — in Syria's civil war. In 2017, they snuck into Rojava to fight alongside the YPG, a Kurdish socialist militia, in order to fight ISIS.

Bertram-Lee didn't end up participating in any firefights. As Jacobin reported, he went through months of YPG's basic training but ended up on a base making dank memes promoting the group's ideology. YPG and its associated political party PKK are committed to the political teachings of Abdullah Öcalan, a Kurdish political prisoner who has advocated for political systems that integrate socialism, democracy, and feminism. The story of Bertram-Lee's time in Rojava is being turned into a movie, Deadline reported this month.

There are other major differences between Bertram-Lee's experience and what volunteers are expecting in Ukraine. While the UK's foreign ministry gave the green light for fighters to go to Ukraine, Bertram-Lee was questioned multiple times by the police when they returned home. And as they pointed out, there are simply far more people going to Ukraine than to Syria.

"The number of foreign fighters who joined YPG that weren't from Turkey was max 500 over about five years," they said. "So the numbers are just completely incomparable."

But there are still similarities. British volunteers who went to fight in Ukraine told Insider they wanted to defend a democratic Europe and couldn't stand that Putin would invade a sovereign country. Bertram-Lee said they personally wouldn't fight for Ukraine, in part, because communist groups are outlawed in the country and they were suspicious of the fascist Azov Battalion fighters in the country's military. And like the volunteers for Ukraine, Bertram-Lee went to Rojava to defend and build a free society that was under threat.

"For me it was, it was about social internationalism," they said. "For YPG, it was an effort to show that this wasn't some kind of narrow Kurdish national struggle, but this was a general struggle against a fascist organization by a socialist party in a long tradition of these sorts of things."

Mamuka Mamulashvili, the commander of the Georgian International Legion of Ukraine's army, which has accepted international fighters for years, previously told Insider that he's cultivated a group of freedom fighters, excluding "religious fanatics" and "Nazis" who want to fight. It's a commitment to ideology, he said, that produces more committed fighters.

"We don't have some extremists or bloodthirsty guys that are coming [and saying] 'Let's kill somebody,'" Mamulashvili said. "We in Georgian Legion have professionals. They are well-educated men, they are ideologists, they know that they're fighting for freedom, which is the main idea of the Georgian Legion."

YPG, too, has focused on recruiting ideologically motivated people, Bertram-Lee told Insider. They said it's important for volunteers to "not be in any way ambivalent" about joining the fight.

"In Rojava, I saw myself as a small part of a very big thing," Bertram-Lee said. "And definitely that's the attitude you should take with you if you decide to go to Ukraine."