Russia’s Federal Investigative Committee has approved a request by Polish officials to carry out another inspection of the wreckage of the Tu-154 plane that crashed outside Smolensk in 2010, killing then President Lech Kaczyński. The review of the plane’s structural debris will take place between September 3 and 7, conducted by specialists from Russia’s Main Forensics Directorate “in the presence of Polish officials.”

Why are we talking about an eight-year-old plane crash?

In Poland, the 2010 Smolensk crash has grown more contentious over the years, straining the country’s historically complicated relationship with Russia. The Moscow-headquartered Interstate Aviation Committee ruled out a terrorist attack, explosion, or fire on board as the cause of the crash, attributing the incident to pilot error and bad weather conditions.

Polish investigators initially agreed that Kaczyński’s pilots made mistakes, but they also placed some blame on the Russian air traffic controllers at Smolensk North Airport.

In 2016, Poland reopened the investigation, exhuming the crash victims’ bodies. In March that year, National Defense Minister Antoni Macierewicz said a terrorist attack could have downed Kaczyński’s plane. In October 2017, Macierewicz said one of the plane’s flight recorders picked up the sound of an explosion.