The offensive of Ukrainian forces has been widening a gap in the frontline for several weeks, the report adds, clarifying that "Ukrainian forces have yet to complete a breakthrough of this defensive layer" with heavy armor and vehicles.
Ukrainian officials have indicated that the series of Russian defensive positions ahead of the Ukrainian advance may be less challenging than the initial Russian defensive layer that Ukrainian forces broke through to the north, said the ISW.
Ukraine announced it had seized back control of the village of Robotyne in early September.
This recent success comes after a week of notable military actions by for Ukraine.
On Thursday, a video came out appearing to show Ukrainian soldiers entering and liberating the village of Andriivka, near Bakhmut.
"Capturing and holding Andriivka — is our path to a breakthrough on the right flank of Bakhmut and the key to the success of the entire further offensive," said Ukraine's Third Assault Brigade, which took part in the push, according to Reuters.
Russia denied Ukraine's advances, saying Ukraine was "unsuccessfully trying to oust Russian troops from the population centers of Klishchiivka and Andriivka," according to Al Jazeera.
ISW's Saturday report, however, states that geolocated footage posted on September 15 confirms that Ukrainian forces have advanced in the Bakhmut area, not only around Adriivka but also the nearby villages of Rozdolivka and Klishchiivka.
Devstating strikes by Ukraine on land and sea
Also on Thursday, an attack in Crimea destroyed Russia's advanced S-400 "Triumf" air-defense system, which is worth over $500 million, using modified Neptune naval cruise missiles.
ISW said this may signal Russia's air defenses in Crimea have "systemic tactical failures" and that Russian forces were "unprepared to intercept missiles with the system or were unable to do so." It was the second strike to obliterate S-400 in Crimea in a few weeks.
On Friday, Ukraine struck and damaged a Russian missile ship off the coast of Crimea. Ukrainian forces told Reuters and Ukrainian media that an experimental sea drone called Sea Baby, was used as part of this attack.
Russia's defense ministry denied any damage and said the attack was repelled and the drone was destroyed, Reuters added.
Ukraine also claimed that its marine drones had struck at lease on of two Russian corvettes in the Black Sea, according to the newspaper Ukrainska Pravda, per ISW.
Earlier in the week, a major Ukrainian strike, using missiles and marine drones, on a Crimean naval base likely dealt a serious blow to the operation of Putin's Black Sea fleet, according to UK intelligence.
Ukrainian forces launched an attack on Wednesday on Russia's Black Sea Fleet base at Sevastopol, striking a submarine and a landing ship, per the UK's Ministry of Defence.
In its latest intelligence update published on Friday, the UK MoD said the two vessels — identified as the landing ship Minsk and the Kilo 636.3 class submarine Rostov-on-Don — were hit while undergoing repairs in dry docks at the Sevmorzadov shipyard.
The attack also put the dry docks vital for maintaining the Black Sea fleet out of action for the foreseeable future.
"The complex task of removing the wreckage from the dry docks will also place the facility out of use for many months," said the UK MoD.
On Saturday, a NATO admiral told the military alliance that "history books will show Ukraine has transformed modern warfare. And they are moving forward every day. Every success is one step closer to victory."