The attack on Kharkiv continued on Wednesday, even as Russia announced that it would be ready to resume talks with the Ukrainian side in the evening.

The Ukrainian leader condemned Russia's escalation of attacks on crowded cities, describing it as an outright terrorist campaign, while U.S. President Joe Biden warned that if the "Russian leader does not pay a price" for the invasion, the aggression will not stop with one country.

"No one will forgive. No one will forget," pledged Ukrainian President Volodymyr Zelensky after the bloodshed on Tuesday in the central square of Kharkiv, the country's second-largest city, and the deadly explosion of the TV tower in the capital. He described the attack on the square as "unconvincing clear terror" and a war crime.

The attack on Kharkiv continued on Wednesday, even as Russia announced that it would be ready to resume talks with the Ukrainian side in the evening. The Russian attack on the regional police and intelligence headquarters continued, according to the Ukrainian State Emergency Service.

The raid destroyed the police building's roof and set fire to the upper floor, and parts of the five-story building scattered into the nearby streets, according to videos and photos published by the Emergency Service.

Biden used his first State of the Union address to highlight the determination of the renewed Western alliance that has worked to rearm the Ukrainian army and adopt harsh sanctions, which he said left Russian President Vladimir Putin more isolated in the world than ever.

Biden said: "Throughout our history, we have learned this lesson — when tyrants do not pay the price for their aggression, they cause more chaos."

While Biden was speaking, a 40-mile (64-kilometer) convoy of hundreds of Russian tanks and other vehicles slowly advanced on Kyiv, the capital with about 3 million residents, as the West feared it might be Putin's attempt to overthrow the government.

As dawn broke on the seventh day of the war on Wednesday, Russia found itself increasingly isolated due to sanctions that plunged its economy into turmoil and left the country nearly friendless, except for a few countries like China, Belarus, and North Korea. Russia's leading Sberbank announced on Wednesday its withdrawal from European markets amid tightening Western sanctions.

As fighting intensified, the humanitarian situation worsened. Nearly 660,000 people fled Ukraine, and countless people took refuge underground.

The death toll was less clear, as neither Russia nor Ukraine announced the number of lost troops. The UN Human Rights office recorded 136 civilian deaths, though the actual number is certainly much higher.

A senior Western intelligence official estimated that 5,000 Russian soldiers have been captured or killed in the largest land war in Europe since World War II.

Many military experts are concerned that Russia may be changing its tactics. Moscow's strategy in Chechnya and Syria was to use artillery and air bombardment to crush cities and fighters.

The British Ministry of Defense said it witnessed an increase in Russian air and artillery strikes on populated civilian areas over the past two days. It also said Kharkiv and Mariupol were besieged by Russian forces and that forces moved into the city center of Kherson, the third city. The Russian Ministry of Defense said it had detained Kherson, but the claim could not be confirmed.

Ukrainian authorities said five people were killed in the attack on the TV tower near central Kyiv. Officials said a TV control room and a substation were shelled and at least some Ukrainian channels stopped broadcasting briefly.

Zelensky's office reported that the Babi Yar Holocaust memorial site, adjacent to the TV tower, was also shelled. A memorial spokesperson said a Jewish cemetery at the site was damaged, where Nazi occupiers killed more than 33,000 Jews in 1941.

Zelensky expressed anger on Wednesday over the attack on Babi Yar and concern over targeting other religious sites of historical significance, such as St. Sophia's Cathedral.

Zelensky said in a speech published on Facebook: "Such a missile strike means for many Russians that Kyiv is completely foreign, it means nothing to them. 'They have orders to erase our history and our country.'"

Russia had previously notified people living near transmission sites used by the Ukrainian intelligence agency to leave their homes. But Russian Defense Ministry spokesman Igor Konashenkov claimed on Wednesday that the air raid on the TV tower did not target any residential buildings. He did not address reported deaths or damage at Babi Yar.

In Kharkiv, with a population of about 1.5 million, at least six people were killed when the administrative building in the Freedom Square area was hit by what is believed to be a missile. The Slovenian Foreign Ministry said its consulate in Kharkiv, located in another large building on the square, was destroyed