Ukrainian President Volodymyr Zelenskyy visited the liberated city of Kherson on Monday and promised the victory there would serve as the "beginning of the end" of the war against Russia.

Residents saw Russian troops withdraw last week then Ukrainian soldiers move in. Zelenskyy addressed a crowd in front of a government building where the Russian flag has been replaced by the Ukrainian colors.

"This is the beginning of the end of the war because you see our strong army. We are step-by-step coming through our country," Zelenskyy said. He has promised to recapture all occupied territory, including the eastern region of Donetsk.

Residents of Kherson do not have any water or power. Many fear they could step on mines that are scattered throughout the city.

Both sides have been fighting in muddy conditions. Analysts from the Institute for the Study of War in Washington said armored units will find it easier when "winter freezes the ground." They said combat is "likely to intensify."

NATO Secretary General Jens Stoltenberg urged caution. "We should not make the mistake of underestimating Russia. The Russian armed forces retain significant capabilities as well as large number of troops," he said.

US and Russian intelligence leaders met in the Turkish capital, Ankara. CIA Director William Burns and Russian foreign intelligence service head Sergei Naryshkin did not discuss an end to the fighting. But Burns warned against bringing nuclear weapons into the war.