Summary
Thousands of Ukrainian troops are taking part in an incursion aiming to destabilize Russia. The Russian army had said about 1,000 Ukrainian troops were deployed in the cross-border incursion.
'This operation has shown that we can go on the offensive, move forward,' official says. Russia has evacuated tens of thousands of civilians from the area.
White House says it is contacting Ukraine to learn more about the "objectives" of the incursion. President Joe Biden in May allowed Kyiv to use American-supplied weapons against targets just across the Russian border.
