Russian military forces have only made “minor advances” since retreating from the Kyiv region and escalating their offensive in eastern Ukraine earlier this month, the British Ministry of Defense said on Monday.

Since the tactical change in what the Kremlin calls its “special military operation” in Ukraine, Russia has so far failed to achieve “a significant breakthrough” in the Donbas region, according to the United Kingdom’s intelligence update. The report noted that Ukrainian forces that remain holed up in Mariupol have “exhausted” Russian units and have prevented them from redeploying.