According to President Zelenskyy, Ukrainian forces are moving towards Kherson.
The supply lines for Russian troops have been damaged by the Ukrainians.
Losing supply routes to Kherson would be a serious blow to Russia.
The president said that Ukrainian forces are moving towards Kherson.
The President's announcement comes as Ukrainian forces claim they have damaged two important bridges across the Dnipro River vital to the lines of supply to Russian troops.
If the Russian forces in Kherson are cut off, it would be a major military and political blow to Russia, according to the British Ministry of Defence.
Heavy fighting took place near Kherson on Saturday.
Reports say that the bridges across the Dnipro River have been damaged by Ukrainian shelling.
The deputy head of the Russian-installed regional authority said that the Daryivskyi bridge was hit by seven rockets on Saturday, but that it still worked.
Serhiy Khlan, an advisor to the region's governor, wrote on Facebook that every bridge is a weak point for logistical support. This is a serious step in the process of freeing Kherson.
Oleksiy Arestovych, the presidential advisor, said there would be no humanitarian corridor for Russian troops to leave Kherson.
"We have a strong temptation to bury them all, but first of all, we do not fight like the Russians, we do not break our word, and second, the Ukrainian armed forces will offer them to surrender," he said.
We won't give a corridor. His fate will be decided if they don't surrender.
If I were a Russian soldier in Kherson, I would be pretty scared.
He said he would be watching Kherson very closely.
The port city of Kherson was seized by the Russians on 3 March. The first major city to fall was it.
Business Insider has an article on it.