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.

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.