British man captured in Ukraine reportedly pictured beaten and handcuffed | Ukraine

He joined the Ukraine military years ago I think.. Correct me if I'm wrong but he is a soldier of that country and not a volunteer.

He is a dual citizen, which I believe Ukraine doesn't formally recognise. The legal situation is a bit blurry. According to the Constitution of Ukraine, Article 4, only one citizenship exists in Ukraine. This does not explicitly deny dual (external) citizenship, so there are citizens of Ukraine who hold dual citizenship.

I also happen to be a dual (Swedish-Ukrainian) citizen, but I have never pressed claim to my Ukrainian citizenship so I think Ukraine would consider me Swedish if I ever went there. Not too smart to claim your second citizenship anyway when there is a war going on in the country. I've heard from my parents that you lose your Ukrainian citizenship when you turn 18, but I haven't been able to find a legal text online that supports it.

Regarding Aslin – the soldier this news article is about – Wikipedia says:

Aiden Aslin is a British-Ukrainian national and current Ukrainian Marine[1] who previously fought with the Kurdish YPG militia in Rojava, northern Syria.[2] His nom de guerre is "Rojhat Rojava" and served in the Lions of Rojava group which is a part of the YPG.[3] In April 2022, he was captured by Russian forces during the Russian invasion of Ukraine.

He was also investigated by UK officials for fighting against ISIS in Syria, together with the YPG:

Aslin was the first foreign fighter to be investigated by the UK police,[11] and gained the support of the public as well as politicians in protesting against his treatment by Nottinghamshire Police.[12] Aslin was questioned under the Terrorism Act on suspicion of engaging “in the preparation to fight against Daesh” and possessing “articles for terrorist purposes in Iraq/Syria”.[13] He was eventually acquitted and returned to Syria for a second tour of duty with the YPG in 2016.[14] Aslin repeatedly called on the international community to do more in the fight against terrorism by supporting the YPG and the Kurdish struggle[15] as well as to do more to stop Turkey's support for ISIS.[16]

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