The German Federal Prosecutor's Office has had a suspected member of the Islamic State terrorist group arrested at Dusseldorf airport, the authorities in the city of Karlsruhe said Saturday.
The 22-year-old man had an arrest warrant out against him and was taken into custody as he returned from Turkey on Friday, they said.
The man is accused of travelling to Syria via Turkey in August 2015 and of joining Islamic State there.
He is suspected of being shown how to use weapons at a training camp and of having obtained an automatic rifle and hand grenades to use in battle.
He is also accused of trying to persuade others living in Germany to join him in the Islamic State-controlled region.