Russia is increasingly relying on a large number of small sabotage groups to pierce through Ukrainian positions as its summer offensive struggles to make significant headway, according to Ukraine’s top military commander.

Moscow’s main strategic objective is to reach the intersection of the eastern Donetsk, Dnipropetrovsk and Zaporizhzhia regions, Oleksandr Syrskyi told reporters in Kyiv on Thursday. Russia has concentrated more than 700,000 soldiers along the entire 1,250 kilometers (777 miles) frontline, he added.