Ukraine is exploiting gaps in Russia's air defenses, which were designed for a different kind of war

• Ukraine struck a Russian gas terminal and weapons plant in drone strikes over the weekend.
• Analysts said Ukraine appeared to be exploiting gaps in Russian air defenses.

Ukraine is exploiting gaps in Russia's air defenses, which were designed for a different kind of war, according to a report.

The Institute for the Study of War, a US think tank, said that Russian air defenses in Leningrad Oblast, near St Petersburg, appeared to be poor.

It said the defenses weren't designed to protect from attacks from Ukraine in the south, but from attacks from the NATO alliance in the West.

Ukraine early on Saturday night struck the Ust-Luga gas terminal near St Petersburg using long-range drones, and hit a military plant in Tula, near Moscow, on Sunday that makes the Pantsir-S air defense systems.

The ISW said the attacks were stretching Russia's air defenses. Moscow is trying to position more air defenses on its western border amid escalating tensions with Ukraine's NATO allies, while also defending against Ukrainian drone attacks from the south.

"Russian forces using short-range systems such as the Pantsir may not be able to cover all important potential targets in Leningrad Oblast without bringing additional systems into the area, and continued Ukrainian strikes in deep rear areas in Russia may thus increase pressure on Russia's air defenses overall," the think tank said.

Ukraine's attack on Saturday followed a drone strike Friday targeting oil depots in Klintsy, about 40 miles north of the Ukrainian border.

A Ukrainian official told Reuters that it had been able to strike an oil depot in St Petersburg on January 18 using a specially produced long-range drone with a range of 775 miles. St Petersburg, Russia's second biggest city, is around 530 miles from Ukraine.

Russia has tried to devastate Ukraine using long-range missile strikes and waves of drone attacks, and both countries are seeking to outrace each other to produce ever faster and deadlier drones and exploit weaknesses in air defenses.

Ukraine initially used drones to attack the occupied Crimea peninsula, but has extended the strikes deep into Russia.

Business Insider has contacted the Russian defense ministry about the ISW's claims.