- Russia deployed upgraded glide bombs on eastern Ukraine, the Institute for the Study of War noted.
- It cited one of Russia's military bloggers for the information.
Russia is likely deploying a new type of "smart" gliding bomb that can destroy bunkers even deep underground, the Institute for the Study of War noted.
It cited one of Russia's military bloggers, the Paratrooper's Diary Telegram channel, describing their use.
The base explosives themselves are not new, but have been given new guidance technology to make them hit more accurately.
The bombs are upgraded versions of the FAB-250, FAB-500, and FAB-1500, named after their respective weights in kilograms.
The ISW, citing the Telegram post, said they can be dropped from Russian jets like the Su-34, Su-30, and Su-35.
FAB bombs are a Soviet design, and variants without upgraded guidance have been seen deployed in Ukraine before.
The difference is the apparent use of laser and satellite guidance systems to improve accuracy, per the ISW's update.
While older versions of the bombs hit targets within about 160 feet, the newer ones are accurate to within 16 feet, it said.
They are said to be able to glide to targets around 120 miles from the point where they are dropped, keeping the planes carrying them away from danger.
The bigger the bomb, the bigger the blast, the ISW explained.
The FAB-250 bomb can now carry an explosive as heavy as 218 pounds with a blast radius of some 400 feet, the ISW said.
It is effective against soldiers and light fortifications. Here is a picture of an un-upgraded version in Ukraine which did not explode:
The FAB-500 bomb weighs 1100 pounds, can carry up to 330 pounds of explosive, and has a blast radius of some 800 feet.
It can destroy buildings, warehouses, and even structures made of concrete, the ISW said.
Here is another photo of an un-upgraded one seen in Ukraine after failing to explode.
The FAB-1500 is the biggest and most deadly. It has a weight of 3,417 pounds and a blast radius of up to 1,600 feet.
This one can hurt targets underground, the ISW said. It said the bomb can destroy bunkers 66 feet below the surface, and blast through reinforced concrete up to 10 feet underground.
Adapted bombs like this have been difficult to counter even with advanced air defenses, Insider reported previously. They are often just too heavy to knock off course.
Oleksiy Melnyk, co-director of foreign policy and international security at the Kyiv-based think tank Razumkov Center, told The Washington Post in September that Ukraine's hi-tech air defense missiles are not designed to deal with the bombs' old, heavy iron structure.
Melnyk told Insider the bombings have caused "huge psychological effects" on the population because a large portion of the damage has been on civilian facilities, and many of the victims have been civilians.
Russia is increasingly using them, wrote Hans Petter Midttun, an expert at the Centre of Defence Strategies, in a post for the Euromaidan Press advocacy group in early October.
Russia pummeled Ukraine with 40 glide bombs in just one night in early October in the eastern Kherson region, he said.