Russia resumed its assault on Ukrainian citie s on Wednesday, including the second largest, Kharkiv, where a strike hit the regional police and intelligence headquarters, wounding three people, according to the Ukrainian state emergency service.

Meanwhile, the two countries were expected to engage in a second round of talks since the start of the invasion late last week.

President Joe Biden warned in his State of the Union address Tuesday night that Russia's aggression wouldn't stop with one country unless its president, Vladimir Putin, paid "a price."

Here's a look at key things to know about the conflict:

POSSIBLE TALKS

A Kremlin spokesman, Dmitry Peskov, told reporters that a Russian delegation would be ready Wednesday evening to resume talks with Ukrainian officials about the war in Ukraine.

Ukrainian Foreign Minister Dmytro Kuleba also said his country was ready.

WHAT'S HAPPENING IN KHARKIV?

Russia's assault on Kharkiv, Ukraine's second largest city, continued with a strike on the regional police and intelligence headquarters, and a university building across the street, according to the Ukrainian emergency service and government officials. Explosions also happened in a central square near other government buildings, including the city council's.

Oleksiy Arestovich, an adviser to Ukrainian President Volodymyr Zelenskyy, said an advance of Russian troops on Kharkiv was stopped, so Russia shelled the northeastern city with rockets and airstrikes in response.

"Kharkiv today is the Stalingrad of the 21st century," said Arestovich, who added that several Russian planes were shot down over the city.

Oleg Sinehubov, head of the Kharkiv regional administration, said 21 people had been killed and at least 112 had been wounded over the previous 24 hours.

WHAT ABOUT KYIV?

The 40-mile (64-kilometer) convoy of hundreds of Russian tanks and other vehicles is on a road to Kyiv, a city of nearly 3 million people. The West feared it was part of a bid by Putin to topple the government and install a Kremlin-friendly regime.

Russian Defense Ministry spokesman Igor Konashenkov said Wednesday that Russia's airstrike Tuesday on the main TV tower in Kyiv was aimed at disabling Ukraine's ability to stage "information attacks."

Konashenkov didn't discuss the five people who Ukrainian officials say were killed in the attack, which damaged a TV control room and power substation and briefly knocked some channels off the air. But he did say no residential buildings were hit.

WHAT ABOUT VIOLENCE ELSEWHERE?

Two cruise missiles hit a hospital in the northern city of Chernihiv, the Ukrainian news agency UNIAN quoted the city's chief health administrator, Serhiy Pivovar, as saying. The hospital's main building suffered damage and authorities were working to determine the casualty toll, he said.

The Chernihiv region's state administration said dozens of nearby homes and a police station were damaged in the strike.

Concern is rising about Ukraine's four operating nuclear power plants.

Arestovich said Wednesday that Russian troops were stopped at the entrance to Energodar, where the Zaporizhzhia nuclear plant is located, and that local authorities were negotiating the plant's safety.

The U.K. Defense Ministry said Tuesday that it had seen an increase in Russian air and artillery strikes on populated urban areas over the past two days. It also said Russian forces had encircled Kharkiv and the southern coastal cities of Kherson and Mariupol.

WHAT DID BIDEN SAY?

Biden used his first State of the Union address to highlight the resolve of a Western alliance that has worked to rearm the Ukrainian military and adopt tough sanctions — including closing U.S. airspace to all Russian flights.

Biden devoted the first 12 minutes of his address to Ukraine, with lawmakers of both parties repeatedly rising to their feet and applauding as he praised the bravery of Ukraine's people and condemned Putin's assault.

WHAT IS THE HUMANITARIAN SITUATION?

It's worsening. Roughly 874,000 people have fled Ukraine and the U.N. refugee agency warned the number could cross the 1 million mark soon. Countless others have taken shelter underground.

Ukraine's State Emergency Service said more than 2,000 civilians have died, though it was impossible to verify the claim. The U.N. human rights office said it had recorded the deaths of 136 civilians, including 13 children, in Ukraine since the Feb. 24 start of the invasion.

The EU is stepping up aid for Ukraine and moving toward granting temporary protection to those fleeing Russia's invasion. The EU Commission said Wednesday that it will give temporary residence permits to the refugees and allow them rights to education and work in the 27-nation bloc. The move would still need the approval of member states, but they expressed broad support for the idea over the weekend.

HOW IS THE RUSSIAN ECONOMY FARING?

Russia has found itself increasingly isolated, hit by sanctions that have thrown its economy into turmoil and left the country practically friendless, apart from a few nations including China, Belarus and North Korea. Biden said the sanctions have left Putin "isolated in the world more than he has ever been."

Leading Russian bank Sberbank said Wednesday that it was pulling out of European markets amid tightening Western sanctions. The bank said its subsidiaries in Europe were facing an "abnormal outflow of funds and a threat to the safety of employees and branches," according to Russian news agencies. They did not provide details of the threats.

The U.S. and EU have levied sanctions on Russia's biggest banks and its elite, frozen the assets of the country's Central Bank located outside the country, and excluded its financial institutions from the SWIFT bank messaging system.

The sanctions and resulting crash of the ruble have left the Kremlin scrambling to keep the country's economy running. For Putin, that means finding workarounds to the Western economic blockade.

China won't impose financial sanctions on Russia, the country's bank regulator said Wednesday. China is a major buyer of Russian oil and gas and the only major government that has refrained from criticizing Moscow's attack on Ukraine.

"We disapprove of the financial sanctions, particularly those launched unilaterally, because they don't have much legal basis and will not have good effects," Guo Shuqing, the chairman of the China Banking and Insurance Regulatory Commission, said at a news conference.

DEVELOPMENTS AT THE UNITED NATIONS

The U.N. General Assembly will vote Wednesday on a resolution demanding that Russia immediately stop using force against Ukraine and withdraw its military from the country, and condemning Moscow's decision "to increase the readiness of its nuclear forces."

The 193-nation General Assembly met Tuesday for a second day of speeches about the war, with more than 110 member states signed up to speak. Unlike the U.N. Security Council, the General Assembly doesn't allow vetoes. And unlike Security Council resolutions, General Assembly resolutions aren't legally binding, though they have clout in reflecting international opinion.

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