Russia blames Western powers for their "betrayal" of Europe in signing the 1938 Munich Agreement that allowed the Nazis to take Czechoslovakia.
The 18-year-old gunman owned a book on American school shooters.
Teen gunman who killed nine lived in a society with extensive gun control measures.
An 18-year-old German-Iranian gunman apparently acted alone, police said.
The alleged assailant, a 27-year-old man who was under arrest and suspected of using drugs, shouted "Allahu Akbar" ('God is Greatest' in Arabic).
Police said they had received information that five to seven suicide bombers were planning to take part in the attack.
The city council upheld a more than decade-old ban on "Stolpersteine," a project of German artist Gunter Demnig.