Can Foreigners Legally Fight For Ukraine?

Updated March 3, 2025
5 min read
Can Foreigners Legally Fight For Ukraine?

Russia’s invasion of Ukraine does not seem to be reaching a resolution anytime soon. Even though talks are being held about neutrality, there are larger constraints that are affecting the peace deal, specifically the insistence by Moscow that Kyiv surrenders a significant amount of its territory to Russia.

In response to this invasion, Ukrainian President Volodymyr Zelensky recently announced the formation of the International Legion of Defense of Ukraine. Prolific images of everyday Ukrainian citizens fighting for their country, joining together as teachers, models, farmers, and more in arms have encouraged people around the world to want to join the Ukraine Army.

Americans Joining Foreign Militaries: The Laws Governing American Foreign Fighters

The U.S. State Department has made it clear that American citizens can join the military of another country. You cannot be hired or recruited while in the United States to serve in the military of another country, but you are allowed to travel to another country and join their military OR apply to join their military through the Embassy.

However, by doing so, volunteer soldiers lose their neutral status. The Neutrality Act dating back to 1794 prohibits citizens from engaging in war against foreign governments who are at peace with America. It carries with it a prison sentence of up to 3 years and can technically apply to joining volunteer armies. However, it is rarely used for prosecution unless there are legitimate links to things like domestic terrorism against America.

This means an individual choosing to join a foreign army or military does not drag the entire U.S. military or NATO military into that war by doing so. There are warnings that fighting against a country with whom the United States is at peace is grounds for voluntarily giving up your citizenship. However, the Supreme Court stipulates that in isolation, foreign military service is not sufficient grounds to strip Americans of their citizenship if they do not intend to relinquish their citizenship.

Similar laws are in place for British, Australian, and Indian volunteers. British citizens traveling to Ukraine to join the fight could be subject to prosecution when they come back. The United Kingdom has a foreign enlistment act from 1870, which prevents citizens from joining foreign militaries fighting countries with whom Great Britain is at peace. The British government has warned its citizens not to travel to Ukraine. 

The Australian prime minister has similarly warned Australian citizens not to join because of the legal uncertainties about foreign combatants. 

Warnings About Foreign Fighters in Ukraine

Technically it is legal for American citizens to join Ukrainian volunteer battalions or the Ukraine volunteer army. That said, the defense department has discouraged Americans from joining foreign militaries, stipulating that the best way to support the people of Ukraine would be to donate to humanitarian organizations trying to provide assistance, such as the Red Cross. Other organizations have contended that Americans joining the Ukraine volunteer army could actually make the situation worse because of the language barrier and increased violence. 

Russia has issued warnings that any foreign fighters who join Ukraine will be construed as Mercenaries. Russia specifically stipulated that foreign Fighters do not get the same protection under international law as lawful combatants, which means Vladimir Putin will try to prosecute anyone caught as a criminal.

Those who are caught could be prosecuted by Russia as criminal mercenaries or face prosecution when they return to their home country. This risk is heightened in situations where war crimes are committed by the foreign fighters who have joined the volunteer battalions. In effect, there are many warnings from the United States government, the British government, the Indian government, the Australian government, and others against foreigners joining the fight in Ukraine.

Steps to Join the Ukraine Volunteer Army

If, in spite of these warnings, foreigners are interested in joining the Ukraine volunteer army, here are steps that can be followed.

1. First, you must apply at a Ukrainian embassy, in person, over the phone, or via email.
2. You will be required to provide documents that prove you have military experience.
3. You must prepare for a zoom interview, and you must submit an application.

IF you are approved for military service because of your background and qualifications, then  here is how to join Ukraine army:

4. You will likely have to bring your own military armor and helmet. You do not have to bring weapons as Ukraine will provide weapons.
5. The Embassy will provide you with information on how to safely travel to Ukraine and what documentation you need.

Note: This is for general information purposes only and not meant as an endorsement of any kind.

Thousands of people have already applied through the Ukrainian Embassy to be foreign fighters. However, more than half of those applicants have been rejected. Even though anyone is technically allowed to volunteer as a foreign fighter in any army, Ukraine is specifically vetting people who have military experience. While it is appreciated that everyday individuals have a desire to help, and everyday individuals have seen the images of like-minded everyday Ukrainian individuals taking up arms, the government is not shouldering the risk of sending anyone and everyone into battle who volunteers.

Conclusions

In conclusion, there are many people from foreign countries who have expressed a desire to join the armed forces and help the people of Ukraine. Even though it is legal to join the Ukrainian battalions, you can’t just hop on a plane and show up with a gun and a helmet. You have to apply through the Ukrainian Embassy and undergo an application and interview to determine whether you have actionable military skills that can be put to use. What’s more, in spite of the legal ability, there is a heightened risk for volunteer firefighters and a significant number of warnings from the US government and private organizations to avoid joining the fight as a private war. 

There are many ways in which Americans can support Ukrainians in need, specifically by donating to the Ukrainian “Come Back Alive” NGO or similar humanitarian organizations that are currently putting together assistance and aid for Ukraine.

Article by Inna Lohvin

Inna Lohvin (Ptitsyna) was a Product Communications Manager for Lawrina. Inna has a law degree and great expertise in legal innovations. Along with the work for Lawrina, Inna is a part of the international community of Legal Hackers, where she gives presentations about the importance of PR and marketing for lawyers.

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