A German soldier went on trial on Thursday after being accused of plotting to attack high-ranking politicians while posing as a Syrian refugee.
Franco Albrecht, 32, allegedly planned to use the attack to stir up anti-migrant sentiment.
In a case that rattled Germany, he was arrested in 2017 while trying to retrieve a pistol he had hidden in a toilet at Vienna International Airport.
Prosecutors say the Bundeswehr lieutenant had taken weapons and explosives from the German army.
At his trial, he denied planning an attack.
"I can assure you I am not a far-right extremist," he said. "I have a clean conscience ... I have never planned any actions to the disadvantage of any person."
His lawyer told the court that Mr Albrecht was the victim of a "public witch hunt" and "character assassination".
He said his client was not a right-wing extremist and had posed as a refugee "in order to highlight security gaps in the system".
Despite speaking no Arabic, Mr Albrecht successfully posed as a Syrian refugee by using make-up to darken his face.
Pretending to be a Christian fruit seller from Damascus, he applied for asylum in his own country under the name David Benjamin.
He commuted from the Illkirch barracks in France, where he was serving in a prestigious Franco-German brigade, to attend asylum hearings, where he communicated through an interpreter.
His double identity was uncovered only upon his arrest in 2017, when police found his fingerprints produced two separate matches.
A serious act of violence that endangers the state
Prosecutors claim Mr Albrecht had planned to use both the pistol and other weapons and explosives to carry out an attack under his false refugee identity.
They believe the targets were Heiko Maas, who was serving as justice minister at the time, deputy speaker of Parliament Claudia Roth, or a human rights activist.
Mr Albrecht is charged with plotting "a serious act of violence that endangers the state" as well as with fraud and illegally possessing weapons and explosives.
If convicted in the trial set to last until August, he could face up to 10 years in prison.
The trial's opening has already been delayed several times by questions over which court would hear the case.
The hearing has laid bare the struggles of Germany's immigration system to cope with the entry of hundreds of thousands of asylum seekers during the refugee crisis of 2015 and 2016.
It strained the relationship between the armed forces and Germany's then-defence minister, Ursula Von Der Leyen, who is now president of the European Commission.
"There would have been a weapon at the site, with fingerprints on it," Ms von der Leyen said at the time.
"We’d have put the prints in the system and have got the match of a Syrian refugee."
Ms Von der Leyen's successor, Annegret Kramp-Karrenbauer, ordered the partial dissolution of a commando force last year after revelations surfaced that some of its members harboured neo-Nazi sympathies.
Following a string of far-right terrorist attacks over the past two years, Interior Minister Horst Seehofer declared right-wing extremism the "biggest security threat facing Germany".
He promised tougher security measures, including a campaign against online hate speech.
