Trench warfare, relentless artillery, gains measured in mere meters, and heavy casualties on both sides. The battlefields of Ukraine resemble those of World War I, but with a new and terrifying reality — the incessant buzzing of drones, harbingers of death and destruction that are constantly watching from above.

The Ukraine war has essentially become “World War I with 21st century ISR [Intelligence, Surveillance and Reconnaissance],” Mark Cancian, a retired US Marine Corps colonel and senior adviser at the Center for Strategic and International Studies, told Insider.

Both Ukraine and Russia have used drones of all shapes and sizes to spy on each other and to strike targets on a scale that’s never been seen before, and it’s changing the face of warfare. Drones are being used to locate enemy positions and direct fire, crash into and destroy buildings in “kamikaze” attacks, and drop bombs on tanks.