Kyiv’s strikes on key bridges linking the annexed Crimean peninsula to southern Ukraine and to mainland Russia are impacting Moscow’s ability to move resources and fend off Ukraine’s ongoing counteroffensive, according to a new assessment.

Ukrainian forces zeroing in on Russia’s logistics in Crimea “are a part of a deliberate interdiction campaign aimed at setting favorable conditions for larger counteroffensive operations,” the Washington D.C.-based Institute for the Study of War (ISW) think tank said on Saturday.

Kyiv’s counteroffensive, now in its third month, has focused on southern and eastern Ukraine, including the annexed Kherson region. But throughout the 18 months of full-scale war and in the years before, Ukraine has vowed to retake Crimea, which Russia has controlled since 2014.

Moscow has accused Ukraine of repeatedly striking the Chonhar Bridge, linking Kherson and Crimea, and the Kerch Bridge, connecting Crimea to mainland Russia.

“Previous Ukrainian strikes on bridges along Russian ground lines of communications between occupied Crimea and occupied Kherson Oblast continue to disrupt Russian logistics,” the ISW said in its latest assessment.

The Chonhar Bridge runs from the Russian military logistics hub at Dzhankoi in northern Crimea into Russian-controlled territory in Ukraine’s Zaporizhzhia region. Britain’s defense ministry previously described Dzhankoi as a “key road and rail junction” vital for supplying Russia’s troops, as well as one of “the most important Russian military airfields in Crimea.”

On Saturday, Russia’s Defense Ministry blamed Ukraine for an “attempted” strike on the Kerch Bridge “using a S-200 surface-to-air guided missile converted into a strike version.”

The Russian-installed governor of Crimea, Sergey Aksyonov, said on Telegram that air defenses had “shot down two Ukrainian missiles in the Kerch Strait area,” adding that the 12-mile bridge stretching across from the Russian mainland to the annexed peninsula was not damaged.

“Another enemy missile was shot down over the Kerch Strait,” he later wrote.

In a statement earlier on Saturday, Moscow said Ukraine had launched 20 drones at Crimea, 14 of which were destroyed by air defenses. The remaining six were “suppressed by electronic warfare,” the Defense Ministry said.

Ukraine’s strikes on the bridges have forced Moscow’s troops to think up new ways to deliver ammunition and supplies from Crimea to its forces in mainland Ukraine, Nataliya Humeniuk, a spokesperson for Ukraine’s southern operational command said, as reported by Ukrainian outlet UNIAN in late July.

“We continue to work on the destruction of what they have already stockpiled, and we are working to ensure that logistics do not allow them to restock,” she said.

Newsweek has reached out to the Russian Defense Ministry for comment via email.