The attack, planned for a concert in Vienna in August 2024, was thwarted, but three gigs in Austria scheduled for that month were canceled.
Swift's fans had flown to Vienna from all over the world to see the star perform there during her world tour.
The now 21-year-old man is said to have planned to use knives or homemade explosives to target the crowd outside the Ernst Happel Stadium where the concert was to take place.
The man is suspected of terrorism and of membership in a terrorist organization, and his defense lawyer has previously said he is expected to plead guilty to most of the charges. He could be sentenced to up to 20 years in prison.
The trial against the man began on Tuesday.
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