Eight alleged neo-Nazis have gone on trial in Dresden, eastern Germany, accused of plotting terror attacks.
Federal prosecutors say the so-called "Revolution Chemnitz" group planned to target immigrants, political opponents and the "economic establishment".
They are said to be members of the neo-Nazi scene in Chemnitz, a city where far-right protests were held last year after a German man was fatally stabbed.
The group allegedly planned a deadly attack in Berlin for 3 October 2018.
Most of the men, aged between 21 and 32, were arrested on 1 October. Prosecutors say the group's plans for obtaining firearms had been intercepted in an internet chatroom. Germany celebrates National Unity Day on 3 October, to commemorate the reunification of the country in 1990.
Chemnitz is in Saxony, a state with one of the highest levels of far-right activism in Germany.
Last month a Syrian man, Alaa Sheikhi, was sentenced to nine and a half years in prison over the fatal stabbing of Daniel Hillig in Chemnitz - the killing that sparked days of unrest in August and September last year. Far-right protesters clashed with activists opposed to them, as police struggled to contain the violence.
Some of the group on trial on Monday are accused of having assaulted foreigners in Chemnitz last September, in a "test run" ahead of the planned 3 October attack.
Support for the far-right Alternative for Germany (AfD) surged after Chancellor Angela Merkel allowed more than a million migrants and refugees to stay in Germany in 2015-2016. Syrians fleeing their country's civil war formed the largest group.
The AfD, campaigning against so-called "Islamisation", is now the largest opposition party in the federal parliament.
Militant groups such as "Revolution Chemnitz" are suspected of plotting attacks to throw Germany into chaos and stage a far-right takeover.
In July last year a neo-Nazi, Beate Zschäpe, was jailed for life over the murder of eight ethnic Turks, a Greek citizen and a policewoman between 2000 and 2007.
She was in a neo-Nazi cell called the National Socialist Underground (NSU). The case shocked Germany because it exposed major failures in the surveillance of such groups.