Russian air defences downed what authorities described as five Ukrainian balloons overnight, the defence ministry in Moscow said Thursday, as the sides kept up long-range strikes that have featured heavily in what has largely become a war of attrition.

Neither Russian nor Ukrainian officials have provided details about the secretive balloons, which Moscow authorities and media have reported on the battlefield in recent weeks. Ukraine’s military has been driving innovation since the war began in February 2022, notably adapting drones for wide use against the bigger Kremlin forces.

According to Russian news reports, the Ukrainian balloons are equipped with a GPS module and carry explosives. They reportedly are harder to detect and could carry a bigger payload than more common small drones. It is not clear if they are helium or hot air or another type of balloon.

The balloons aren’t able to maneuver in the air. The GPS module is likely used to coordinate the release of explosives if the balloon floats over a specific area, with the aim of sowing panic on the ground and distracting Russian air defence assets.

Three Ukrainian balloons and one drone were downed over the Voronezh region, which borders the Moscow-occupied Luhansk region of Ukraine, and two balloons were intercepted in the Belgorod region of Russia next to Ukraine, the Russian defence ministry said.

As well as the balloons, Russia claimed it intercepted two Ukrainian tactical missiles, 19 rockets fired from multiple rocket launchers and 16 drones during the night.

The defence ministry also said that three drones were destroyed over the Rostov region, both in southern Russia.

Balloons brought down by Russian air defences earlier this week in the Lipetsk and Kursk regions carried mortar mines, Russian news reports said.

Ukraine is encountering difficulties on the battlefield against a bigger and better-equipped army as key Western military support for Kyiv has tapered off. Crucially, further U.S. aid is stalled in Congress, just as Ukraine braces for a major Russian offensive that could come as early as next month.

Ukraine has increasingly aimed at distant targets behind the front line, striking Russian rear bases and infrastructure.

But Kyiv officials are pleading with the country’s Western partners to send more air defence systems as Russian missile and drone attacks pummel urban areas and the power grid.

The death toll from a Russian missile attack on a downtown area of the northern Ukrainian city of Chernihiv on Wednesday rose to 18, with 78 people injured, authorities said Thursday.

Ukraine President Volodymyr Zelenskyy appealed late Wednesday to European Union leaders for more air defence equipment, and Foreign Minister Dmytro Kuleba told a meeting of G7 foreign ministers in Italy on Thursday that “the one and the only issue on my agenda here … is air defence.”

Ukraine’s air force said it downed all 13 Shahed drones launched by Russia at Ukraine overnight.