Prominent activist and publisher Jimmy Lai on Tuesday pleaded not guilty to three charges of sedition and collusion with foreign countries in a landmark national security trial in Hong Kong.

Lai was arrested during a crackdown on dissidents following huge pro-democracy protests in 2019. He faces possible life imprisonment if convicted under a sweeping national security law imposed by Beijing. The trial is expected to last about 80 days without a jury.

The 76-year-old media tycoon who founded the now-defunct Apple Daily newspaper faces one count of conspiring to print seditious publications to incite hatred against the Chinese and Hong Kong governments, as well as two counts of collusion with foreign countries to call for sanctions and other hostile actions against China and Hong Kong.

Flanked by three prison officers, Lai formally pleaded not guilty to the charges read to him, shortly after the court rejected a last-ditch attempt by his counsel to throw out a sedition charge.

Prosecutor Anthony Chau in his opening statements described Lai as a “radical political figure” and the “mastermind” behind a conspiracy. Chau also said that Lai had used his media platform to advance his political agenda.

Clips of interviews that Lai gave to foreign media as well as speeches at events between 2019 and 2020 were also played in court. In the video, Lai called for support from foreign governments and urged U.S. officials as well as then-President Donald Trump to impose “draconian” measures on China and Chinese officials in retaliation for imposing the national security law and restricting freedoms in Hong Kong.

His prosecution has drawn criticism from the United States and the United Kingdom. Beijing has called those comments irresponsible, saying they went against international law and the basic norms of international relations.

The Inter-Parliamentary Alliance on China, or IPAC, an international political group that’s critical of China’s human rights record and foreign policy, said Lai’s trial “fabricated” evidence that the media mogul was involved in its work.