Seismometers are generally used by the research community to study local or distant earthquakes, but seismograms also contain critical observations from regional1,2 and global explosions3, which can be used to better understand conflicts and identify potential breaches of international law. The large overpressure generated by an explosion, shakes the Earth’s atmosphere and subsurface, and the resulting ground motion can be recorded by seismometers, while the infrasound signals that propagate through the atmosphere can be detected by microbarometers. While this technology is used by the International Monitoring System4 to monitor nuclear explosions as part of the Comprehensive Nuclear Test Ban Treaty, the detection and location of lower-yield military attacks requires a network of sensors much closer to the source of the explosions. Without dedicated sensor deployments, such networks are rarely available for conflict monitoring. Obtaining comprehensive and objective data that can be used to effectively monitor an active conflict zone therefore remains a significant challenge. We demonstrate how seismic waves generated by explosions in northern Ukraine can be recorded by a local network of seismometers and used to automatically identify individual attacks in close to real-time, providing an unprecedented view of an active conflict zone. Between February and November 2022, we observe over 1200 explosions from the Kyiv, Zhytomyr and Chernhiv provinces, providing accurate origin times, locations and magnitudes. We identify a range of seismo-acoustic signals associated with various types of military attacks, with the resulting catalogue of explosions far exceeding the number of publicly reported attacks5. Our results demonstrate that seismic data can be an effective tool for providing accurate and objective data in real-time from an ongoing conflict. We anticipate that the implementation of seismic-based monitoring techniques can provide invaluable information about potential breaches of international law.