Foreign Minister Margus Tsahkna said the conclusion was drawn from information collected by Estonia's Internal Security Service, according to Radio Liberty and Current Time.
The fire broke out in a company hangar on Betooni Street in the Lasnamäe district on the night of August 15. Company representatives said the blaze did not disrupt its delivery schedule, including supplies for Ukraine.
Estonia's Prosecutor's Office reported the detention of three suspects. Two were detained in Latvia and handed over to Estonia in mid-September, where they were placed in custody. Tsahkna said the detainees no longer pose a threat to the country's national security.
On September 29, Estonia's Foreign Ministry summoned Russia's chargé d'affaires, Lenar Salimullin. Russian authorities have not yet commented on the accusations.
Milrem Robotics manufactures THeMIS unmanned ground vehicles and supplies them to Ukraine. No damage was reported after the fire.
Tsahkna described the incident as part of a broader Russian campaign across Europe aimed, he said, at intimidating countries in the region and weakening support for Ukraine. He said Estonia would strengthen both its support for Ukraine and pressure on Russia.
The Telegraph previously reported, citing sources in Western intelligence, on Russia's possible involvement in the Milrem Robotics fire. The outlet reported a wave of sabotage operations calibrated to remain below the threshold for invoking NATO's collective defense clause. Among such episodes, The Telegraph cited a fire at a drone factory in the Czech Republic in March, an attempted arson at a radio frequency scanner factory in Lithuania, and explosions at ammunition plants in Bulgaria and Italy in August.