Biden touts Western strength as Russia bombards Ukraine

President Joe Biden hailed the steadfast Western alliance against Russia's invasion of Ukraine on Tuesday as air strikes pummeled populated areas in the heart of the US ally's second city, raising the civilian toll of the week-old war.

Despite sanctions and warnings of a humanitarian crisis, the fresh assaults on a residential block in Kharkiv came as the US leader was preparing to steel the American public's resolve for the turmoil ahead.

Biden had planned to tout his policy successes during his annual State of the Union address, discuss how the United States had turned a corner on the pandemic and outline what he wanted to accomplish in the coming months.

But much of that was upended by one of the most significant crises in the geopolitical landscape since the end of the Cold War, after Russia ordered tens of thousands of troops into Ukraine.

"Putin's war was premeditated and unprovoked," Biden said in prepared remarks released ahead of his annual address, on day six of Russia's invasion.

"He rejected efforts at diplomacy. He thought the West and NATO wouldn't respond. And, he thought he could divide us here at home. Putin was wrong. We were ready."

Earlier Biden had spoken on the phone to Ukrainian president Volodymyr Zelensky, who accused Moscow of "state terrorism" and tweeted: "We must stop the aggressor as soon as possible."

Although Russia has denied targeting civilian infrastructure, British Prime Minister Boris Johnson called the bombardment of Kharkiv "absolutely sickening" and reminiscent of massacres of civilians in Sarajevo in the 1990s.

Eight people were reported dead in a residential building in the city and officials said 10 had been killed by Russian shelling on a local government complex.

A strike on the main TV tower in Kyiv also killed five people and knocked out some state broadcasting, Ukrainian officials said, but left the structure intact.

Fresh explosions were heard late Tuesday in Kyiv and Bila Tserkva, 50 miles (80 kilometers) to the south, according to local media.

News outlets also reported Russian missiles damaging residential buildings and a hospital in Zhytomyr, citing the major transport hub's mayor Sergei Sukhomline.

The International Criminal Court has opened a war crimes investigation against Russia. Ukraine says more than 350 civilians, including 14 children, have been killed in the conflict.

In southern Ukraine, the city of Mariupol on the Azov Sea was left without electricity after bombardment, while Kherson on the Black Sea reported Russian checkpoints encircling the city.

In a key victory for Moscow, Russia's defense ministry said its troops had linked up with pro-Moscow rebel forces from eastern Ukraine along the Azov Sea coast.

But Ukrainian forces say despite incursions by "sabotage groups," Russian forces have yet to capture a major city.

During a visit to an airbase in Poland, NATO chief Jens Stoltenberg said Putin had "shattered peace in Europe."

Zelensky meanwhile reiterated an urgent appeal for his country to be admitted to the European Union.

More than 660,000 people have fled abroad, the UN refugee agency said, estimating that a million people are displaced within ex-Soviet Ukraine, which has a population of 44 million.

Russia has defied international bans, boycotts and sanctions to press ahead with an offensive it says is aimed at defending Ukraine's Russian speakers and toppling the leadership.

Germany has already promised arms for Ukraine, while the EU said, in a first, that it will buy and supply arms to the country.

But fears are growing of an all-out assault to capture Kyiv, a city of 2.8 million.

Satellite images provided by US firm Mazar showed a 40-mile build-up of Russian armored vehicles and artillery north of the capital.

Inside Kyiv, makeshift barricades dotted the streets and residents lined up outside the few shops open to buy essentials.

Russia's invasion has triggered a widening international sporting ban and Western nations have moved to further isolate Russia, responding with an intensifying diplomatic, economic and cultural backlash.

Biden will use his speech to announce the United States is joining Canada and several European nations in banning Russian aircraft from its airspace, US media reported.

Apple on Tuesday stopped all sales in Russia. And the European Union banned Russian state media outlets RT and Sputnik from broadcasting in the bloc while also barring some Russian banks from the SWIFT bank system.