Pictures have appeared on social media showing work in Ukraine to turn a tethered aerostat – what is more colloquially called a balloon – into an elevated platform for launching kamikaze drones at incoming long-range one-way attack drones.

Massive drone strikes on Moscow left a trail of destruction in residential areas in Ukraine’s largest ever attack on the city according to local officials. The attacks come as the U.S. and Ukraine delegations are engaged in pivotal negotiations in Saudi Arabia over a possible minerals deal in exchange for security guarantees.

The Ukrainian military said on Wednesday that Russia launched three missiles and 133 drones in an overnight attack. It said the air force shot down 98 drones. Another 20 drones did not reach their targets,