The refinery in Novoshakhtinsk in Russia's Rostov region is located around 15 kilometres from the Ukrainian border, the ISW said in its latest analysis of the war in Ukraine on Thursday.
According to the US think tank, the strike on Wednesday was "likely an attempt to disrupt Russian logistics and fuel supply to Russian operations in eastern Ukraine.”
There are unconfirmed reports that the attack was carried out with a kamikaze drone, the ISW said.
Russia improves air defences in Donbas, Ukraine air force remains active
Meanwhile, Russia has improved its air defence capabilities, causing Ukraine to stop using Turkish Bayraktar drones, which operated to great effect in an earlier phase of the war, the think tank said.
It added: “Ukrainian officials are reportedly increasingly concerned that US-provided Gray Eagle strike drones will also be shot down by reinforced Russian air defence over the Donbas.”
However, Ukraine’s aircraft and armed drones remain effective in other areas, successfully striking several targets in the Kherson Oblast over the past week, according to the US think tank.
Russian pressure on Ukraine’s Lysychansk-Severodonetsk pocket
At the same time, Russian forces have been advancing on the eastern city of Lysychansk in the Donbas, according to the UK Ministry of Defence.
In their latest intelligence update, the UK analysts wrote on Thursday: “Since June 19, Russian forces have highly likely advanced over 5 km towards the southern approaches of the Donbas city of Lysychansk.”
The British Ministry of Defence added: “Russia’s improved performance in this sector is likely a result of recent unit reinforcement and heavy concentration of fire.”
“Russian forces are putting the Lysychansk-Severodonetsk pocket under increasing pressure with this creeping advance around the fringes of the built-up area," the UK analysts also said.
However, Russia’s efforts “to achieve a deeper encirclement to take Western Donetsk Oblast remain stalled,” according to the defence ministry in London.
'Aggressor continues to block civilian shipping'
Meanwhile, the General Staff of the Armed Forces of Ukraine reported on Thursday: “In the Donetsk direction, the enemy is concentrating its main efforts on establishing full control over the city of Severodonetsk, conducting offensive operations to surround our troops near the city of Lysychansk, and blocking the main logistics routes.”
Ukraine’s army command also said that "as regards the Kramatorsk, Avdiivka, Kurakhivka, Novopavlivka and Zaporizhzhia directions," Russian forces were carrying out shelling "in order to restrain the actions of units of the Defence Forces and prevent their transfer to other directions.”
Elsewhere, “the aggressor continues to block civilian shipping in the northwestern part of the Black Sea,” Ukraine’s General Staff reported.
It added: “Five missile cruise missile launchers (up to 40 missiles in total) are ready for use in the Black Sea.”
Thursday is day 120 of the Russian invasion of Ukraine.
Source: PAP, facebook.com/GeneralStaff.ua, understandingwar.org