Nearly 20,000 foreign volunteers have signed up to fight alongside Ukrainian forces against the Russian invasion, according to Ukrainian officials.
There is even a website to guide foreign fighters to enlist with an international legion set up by the defence ministry.
Some countries, including the UK, warn that any of its citizens who travel to take part in combat could be prosecuted under anti-terror legislation.
BBC’s Parham Ghobadi reports from the Polish-Ukrainian border.
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