HAMBURG, Germany (AP) — A German court on Tuesday rejected a defense request to end the trial of a former Ukrainian army officer who is accused of damaging the Nord Stream gas pipelines built to carry Russian gas to western Europe in blasts four years ago.

Serhii Kuznietsov, 50, went on trial at the Hamburg state court on Oct. 14, charged with causing an explosion, damaging property, disrupting public service and being an “accomplice to war crimes” by attacking civilian infrastructure.

He is alleged to have been the ringleader of the attack on the Nord Stream gas pipelines, considered one of Europe’s biggest acts of sabotage since World War II.

His lawyers swiftly filed a motion to dismiss the charges. They argued that Kuznietsov was still an active duty soldier and as such was obligated by Ukrainian law not to speak for reasons of secrecy linked to national security, and that under German law anyone who can't speak out can't be convicted.

The court dismissed the motion on the trial's second day of hearings on Tuesday, German news agency dpa reported. It said that the defendant's defense wasn't limited under German law, and that freedom to testify in Germany isn't limited by a foreign country's conditions of service.

The undersea explosions on Sept. 26, 2022, ruptured the Nord Stream 1 pipeline, which was Russia’s main natural gas supply route to Germany until Moscow cut off supplies in August 2022, months after launching its full-scale invasion of Ukraine. They also damaged Nord Stream 2, which never entered service because Germany suspended its certification process shortly before Russia’s all-out invasion of Ukraine.

The suspect allegedly organized and carried out the detonation of at least four bombs between 14 and 27 kilograms (around 31 to 62 pounds) at a depth of 70 to 80 meters (230 feet to 263 feet) near the Danish island of Bornholm.

Kuznietsov was detained last year in Italy. He was publicly named in extradition proceedings that led to his transfer to Germany in November.

Ukrainian President Volodymyr Zelenskyy has denied allegations that his country was involved in the pipeline blasts.