Days before the leaders of Russia and the U.S. hold a summit meeting in Alaska, Moscow’s forces breached Ukrainian lines in a series of infiltrations this week in the country’s industrial heartland of Donetsk.

Russian ship "Port Olya 4" loaded with drone parts and ammunition from Iran could have been hit, Ukraine's military said.

The Ukrainian military said on Saturday that it had pushed Russian forces back by about 2 kilometres (1.2 miles) on part of the Sumy front in northern Ukraine. There was no immediate comment from Russia,