German authorities are investigating a series of fires and break-ins at power substations across the country, raising concerns about the security of the national power grid. The latest incident occurred in Berlin’s Mitte district, where a fire broke out at a construction site and spread to a transformer substation early Monday morning. Firefighters worked through the night to control the blaze, while police examined the site for clues. The cause of the fire remains unclear, and no immediate connection to the other incidents has been established. The events in Berlin follow a major police operation in the western city of Wesel, where authorities discovered "irregularities" at the Niederrhein substation, including a hole cut in an exterior security fence. According to the newspaper Bild, a helicopter was seen circling the area late Sunday as police searched for evidence. It is not yet known if any technical equipment was damaged or tampered with. These incidents come after similar sabotage attempts in other regions, including an attempt to short-circuit a transformer in Dormagen near Dusseldorf and vandalism at a substation in Bergheim near Cologne. In the eastern state of Saxony, police discovered suspected explosives or incendiary devices on overhead power lines in the Goerlitz district, prompting a security operation in the Lusatian lignite mining and power generation region. Additionally, high-voltage power lines at a critical node in Brandenburg were recently damaged in what appears to be an act of sabotage. In Ganderkesee, a transformer station was cordoned off after police found suspicious circumstances. The series of attacks has intensified concerns about the vulnerability of Germany’s critical infrastructure, especially after Berlin accused Russia of responsibility for a failed drone attack at Halle/Leipzig airport last month. Police are also searching for a 48-year-old man who allegedly sent letters claiming responsibility for the sabotage attacks. The man cited opposition to fossil fuels as his motive, and officials have labeled the case as an example of "climate extremism." Federal Interior Minister Alexander Dobrindt has also reiterated claims that Russia is behind a series of hybrid attacks in Germany, though Russia has denied these allegations. In response, Germany is planning a range of measures to strengthen its defenses against drone attacks, cyber intrusions, and other forms of sabotage.