The court convicted the teenager of attempted murder and supporting ISIS.
Police arrested the Austrian suspect, a 17-year-old with Albanian roots, after tip-offs.
The head of the far-right party in Thuringia described the memorial as a "monument of shame" in Dresden.
In an interview with the Handelsblatt newspaper to appear on Tuesday, Gabriel said, "If Trump starts a trade war with Asia and South America, it will open opportunities for us."
Police said the man had links to a second suspect arrested in Vienna.
A speech by Bjoern Hoecke, the AfD's leader in the eastern state of Thuringia, on Tuesday triggered anger across Germany and even caused one member of the radical Left party to report him for incitement to racial hatred.
The president-elect focused on European allies in a round of interviews.
European nations and NATO are setting up centers to identify "fake news", bolstering cyber defenses and tracking use of social media.
Government ministers say new measures will make it easier to deport failed asylum seekers and tag extremists.
German Vice Chancellor Sigmar Gabriel says austerity policies have threatened EU relationships.
Chancellor Angela Merkel has been under pressure for liberal refugee policies.
Michael J. Bazyler's article for Newsweek helped a grandmother discover her father's stolen Warsaw property.
The suspect is accused of scoping targets such as the Brandenburg Gate and Reichstag building.
Anis Amri, 24, plowed a truck through a Berlin Christmas market on Dec. 19. Islamic State claimed responsibility for the attack.
Anis Amri had contact with preacher Abu Walaa's network, a German security source tells Newsweek.
Protection increased at the Vatican and near churches throughout Italian cities as authorities probe Anis Amri's connections within the country.
Anis Amri said that ISIS supporters would seek revenge on what he called "crusaders" in Europe.
The brothers are thought to have planned an attack on a mall close to the Dutch border.
It is harder to be cruel to someone with whom you have made a genuine connection.
Police released the main suspect on Tuesday, citing a lack of evidence.