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.

Small groups of Russian troops have pierced parts of Ukraine’s defenses in its eastern Donetsk region, according to local officials, as Russia appears to be making an 11th-hour dash to snatch as much territory as possible ahead of the planned meeting between President Vladimir Putin and his US counterpart Donald Trump on Friday.

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,