Russia's Defense Ministry says its forces have seized five border villages in eastern Ukraine's Kharkiv region.

Russian ground troops crossed the border from the north and entered Kharkiv on Friday while carrying out a large-scale shelling offensive.

Kharkiv Governor Oleh Syniehubov said on Saturday that fierce fighting has forced the evacuation of about 2,000 residents. He claimed that Ukrainian forces had blocked Russian forces from advancing.

In a video released on Friday, Ukrainian President Volodymyr Zelenskyy said his government is sending more forces toward Kharkiv. He said any attempted invasion by Russians will be disrupted.

The Ukrainian military said on Saturday that fierce fighting against Russian forces continued in the eastern region of Donetsk and elsewhere.

In an assessment report released on Friday, the Institute for the Study of War, a US think tank, says "Russian forces will likely leverage their tactical foothold in northern Kharkiv in the coming days to intensify offensive operations."

The think tank's report adds that "Russian offensive operations along the Kharkiv international border likely have the strategic objective of drawing and fixing Ukrainian forces to this axis to enable Russian advances in other areas of eastern Ukraine."