Vladimir Putin’s war on Ukraine has produced some strange and unexpected results, not least the rush among Western citizens to join President Volodymyr Zelenskyy’s armed forces.

Ukrainian defense officials claim that over 20,000 individuals from 52 nations have volunteered to join the Ukrainian armed forces resisting the Russian invasion, perhaps the most notable volunteer effort since the International Brigades during the Spanish Civil War.

Among them are US software developers, Canadian cooks, numerous ex-service personnel, and even (the UK government has admitted) a soldier from one of Britain’s most venerable regiments, the Coldstream Guards, who is reported to have gone absent without leave to head for Ukraine. At least three other serving UK personnel have done likewise; the government has pledged to prosecute them on their return.

Russia has responded with threats, trying to scare and sway potential volunteers to reconsider, and threatening repercussions if captured by Russian forces. Russia says that those joining the Ukrainian armed forces are bandits, criminals, and mercenaries and will be punished accordingly.

Defense Ministry spokesperson, Igor Konashenkov, said on March 3 that any foreign volunteer taken in Ukraine will not be accorded prisoner of war (PoW) status, but will be treated as a law-breaker accountable for their acts. Konashenkov hinted at executions by stating that, “at best, they can expect to be prosecuted as criminals.” Naturally, if that is the best-case scenario, then the worst-case scenario would suggest execution as a possible outcome.

In fact, international law is clear and applies to Russia’s treatment of PoWs. Under the Geneva Convention, article 4, reads; “Prisoners of war, in the sense of the present Convention, are persons belonging to one of the following categories, who have fallen into the power of the enemy: Members of the armed forces of a Party to the conflict as well as members of militias or volunteer corps forming part of such armed forces.”

As long as these volunteers themselves follow the laws of armed conflict, they are by international law protected as prisoners of war (PoW). There is no ambiguity about this: those who volunteer to join the Ukrainian armed forces are protected by the Geneva Convention and international humanitarian law. There is an established legal doctrine, and there is no space for contrarian interpretation.

The volunteers now pouring into the ranks of the Ukrainian armed forces may not have a direct strategic impact, but it has a far-reaching catalytic effect on the Ukrainian will to fight and their homeland’s perception of the war. That goes a long way to explaining why Putin and Russian outlets portray the volunteers as criminals that Russian authorities will prosecute.

Volunteering for war sends a strong message. First, there is a general assumption that dedicated individuals volunteered because they find the war a just cause. Volunteers help build a morally higher ground; their presence supports the narrative of the force they join, and the volunteers strengthen the morale and fighting spirit of the defenders.

The International Brigade of the Spanish Civil War from 1936-39, drew as many as 60,000 left-wing volunteers, mostly from Europe and North America (perhaps because of the political history, Ukraine instead refers to a foreign legion.) The fighters believed they were defending the Spanish people from a fascist government, and described their actions as a moral obligation. Many Swedes, and others, joined the Finnish Army as volunteers in the Winter War 1939-1940 when Stalin’s Communist Soviet Union attacked peaceful and democratic Finland. I met one of these Swedish volunteers in my younger years, and when asked why he volunteered, he simply answered, “it felt the right thing to do.”

Any Ukrainian who sees French, British, American, Spanish, Brazilian, from wherever they come, volunteers joining their resistance will solidify the notion that the war is not between Ukraine and Russia; but between good and evil. Predictably enough, Putin, his commanders, and propagandists are troubled by the prospect of thousands of volunteers supporting the Ukrainian narrative, their cause, and strengthening the Ukrainian will to endure.    

Second, the volunteers link Ukraine’s resistance to the volunteer’s home country’s public opinion, which disseminates the Ukrainian cause, directly impacting the perception of a war on foreign soil. That is amplified by social media: the impact of TikTok, Instagram, Facebook, and other outlets must have taken Kremlin by surprise, and it is evident — for example — that social media have driven the British support for military aid to Ukraine. The hashtag #BackBorisJohnson is an example; military aid to Ukraine is converted to the currency politicians trade in – public support (the UK government’s standing has risen since the war began on February 24.) The human stories, the TikTok videos, and the tweets fuel the feedback loop demanding more military aid to Ukraine.

From a Kremlin perspective, the volunteers exacerbate foreign military aid to the Ukrainian resistance. Volunteers become tangible evidence that foreign military aid protects a targeted population, a receipt for supporting governments, and enables the push for continued support to Ukraine. As Russian elite forces are becoming worn down, reservists and second-tier units will continue the assault, casualties rise, and putting a halt to foreign military aid becomes a top priority.

According to the official Russian storyline, the volunteers increase foreign involvement, even if these are private initiatives, and become a vital component (albeit not government-backed) to create a narrative to justify foreign military aid to Ukraine.

The threats of harsh punishments and insinuating death sentences to deter foreign volunteers from joining the Ukrainian armed forces is a way to intercept the flow of volunteers — and yet, in many ways, it is already too late for Russia. If it carries out its threats and treats foreign volunteers as criminals, Western public opinion may simply become more enraged, seeing the victims as martyrs to their cause.

Jan Kallberg, Ph.D., LL.M., has been focused on cyber for several years. He is a faculty member at New York University and George Washington University. His works have appeared in Joint Forces Quarterly, Strategic Studies Quarterly, IEEE Security & Privacy, and IEEE Access. Follow him at cyberdefense.com and @Cyberdefensecom.

The views are personal opinions and do not reflect any employer’s position.