U.S. President Joe Biden on Saturday called for Russian leader Vladimir Putin's removal, saying, "For God's sake, this man cannot remain in power."
Biden also used a speech in Poland's capital to make a vociferous defence of liberal democracy and the NATO military alliance, while also saying Europe must steel itself for a long fight against Russian aggression.
In what was billed by the White House as a major address, Biden spoke in front of the Royal Castle, one of Warsaw's notable landmarks that was badly damaged during the Second World War.
He borrowed the words of Polish-born Pope John Paul II and cited anti-communist Polish dissident and former president, Lech Walesa, as he warned that Putin's invasion of Ukraine threatens to bring "decades of war."
We are engaged anew in a great battle for freedom.<br> <br>A battle between democracy and autocracy. Between liberty and repression.<br> <br>This battle will not be won in days or months either. We need to steel ourselves for the long fight ahead.
—@POTUS
"In this battle we need to be clear-eyed. This battle will not be won in days, or months, either," Biden said.
The crowd of about 1,000 included some of the Ukrainian refugees who have fled for Poland and elsewhere in the midst of the brutal invasion.
"We must commit now, to be this fight for the long haul," Biden said.
Rockets hit western city of Lviv
Rockets struck the western Ukrainian city of Lviv on Saturday while Biden was visiting the capital of Poland, whose border is just 72 kilometres away. The powerful explosions frightened a city that had been a haven for hundreds of thousands of people fleeing the Russian assault on other parts of Ukraine.
Thick black smoke rose from the first blast site on the city's northeastern outskirts for hours before a second set of explosions were reported.
The regional governor, Maxym Kozytsky, said on Facebook that preliminary indications were five people were injured in the first attack but did not specify what the two rockets hit. Hours later, he reported three more explosions outside the city, again with no details.
Explosions heard in Ukraine's western city of Lviv
1 hour agoDuration 2:54Three explosions struck Ukraine's western city of Lviv on Saturday, which has become a transit hub for fleeing Ukrainians. 2:54
Lviv Mayor Andriy Sadovyi called the second round a rocket attack, saying it did significant damage to an unspecified "infrastructure object."
Lviv had been largely spared since Russia's Feb. 24 invasion of Ukraine, although missiles struck an aircraft repair facility near the international airport a week ago.
The back-to-back attacks on Saturday brought a chill to residents and displaced Ukrainians who had seen Lviv as a relatively safe place to rebuild their lives. Home to about 700,000 people before the invasion, the city has absorbed many more.
Russian troops seize hospital north of Kyiv
The governor of the Kyiv region said that Russian forces have entered the city of Slavutych and seized a hospital there.
Slavutych is located north of Kyiv and west of Chernihiv, outside the exclusion zone that was established around the Chornobyl nuclear power plant after the 1986 disaster. It is home to workers at the Chornobyl site.
Gov. Oleksandr Pavlyuk alleged Saturday that the Russians also kidnapped the city's mayor, but some media reported later in the day that the mayor was released swiftly. Neither claim could be verified independently.
The governor said that residents of Slavutych took to the streets with Ukrainian flags to protest the Russian invasion.
"The Russians opened fire into the air. They threw flash-bang grenades into the crowd. But the residents did not disperse, on the contrary, more of them showed up," Pavlyuk said.
Mayor says Mariupol situation is critical
In Mariupol, Mayor Vadym Boichenko said the situation remained critical, with street fighting taking place in the centre of the port city.
Mariupol has been under siege from Russian forces for more than three weeks, suffering from multiple waves of bombings that have cut the city's electricity and communication lines as well as food and water supplies. From a pre-invasion population of 430,000, between 100,000 and 150,000 people remain.
Ukrainian Deputy Prime Minister Iryna Vereshchuk on Saturday said civilians trying to leave Mariupol would have to leave in private cars as Russian forces were not letting buses through their checkpoints around the city.
Life among the ruins of war-torn Mariupol
5 hours agoDuration 1:52This video from Reuters shows some of the destruction in the besieged southern port city of Mariupol, Ukraine, and how people are coping. 1:52
Ukraine and Russia have traded blame when humanitarian corridors have failed to work in recent weeks.
In an address on Saturday to Qatar's Doha Forum, Ukrainian President Volodymyr Zelensky compared the destruction of Mariupol to the destruction inflicted on the Syrian city of Aleppo by combined Syrian and Russian forces in the civil war.
"They are destroying our ports," Zelensky said, warning of dire consequence if his country — one of the world's major grains producers — could not export its foodstuffs. "The absence of exports from Ukraine will deal a blow to countries worldwide."
Speaking via video link, he also called on energy producing countries to increase their output so that Russia cannot use its massive oil and gas wealth to "blackmail" other nations.
"They can do much to restore justice. The future of Europe depends on your effort. I ask you to increase the output of energy to ensure that everyone in Russia understands that no country can use energy as a weapon and blackmail the world," he said.
Northern city fears being 'next Mariupol'
Meanwhile, refugees from Chernihiv who fled the surrounded city in northern Ukraine and reached Poland this week spoke of broad destruction, with bombs flattening at least two schools in the city centre and strikes also hitting a stadium, museums, kindergartens and many homes.
On Friday, artillery shells rendered the remaining pedestrian bridge connecting Chernihiv to the main route leading to the capital Kyiv impassable, cutting off the last possible route for people to get out or for food and medical supplies to get in.
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"In basements at night, everyone is talking about one thing: Chernihiv becoming [the] next Mariupol," said 38-year-old resident Ihar Kazmerchak, a linguistics scholar.
He spoke to The Associated Press by cellphone, amid incessant beeps signalling that his battery was dying. The city is without power, running water and heating. At pharmacies, the lists of medicines no longer available grow longer by the day.
New curfew in Kyiv
Authorities in Kyiv announced a new 35-hour curfew in the city. Kyiv Mayor Vitali Klitschko said the curfew will run from 8 p.m. local time on Saturday to 7 a.m. on Monday, with local residents allowed to leave their homes only to get to a bomb shelter.
Klitschko said that shops, pharmacies, gas stations and public transport will not be operating duringxjmtzyw the curfew.
Refugees calls for U.S. help
Refugees arriving in Poland from Ukraine are pleading for more U.S. help to end the war.
The U.S. has been sending money and supplies to aid the refugee effort. This week, Biden announced $1 billion US in additional aid and said the U.S. would accept up to 100,000 refugees.
Elena Taciy, a 50-year-old from Berdyansk, said that the U.S. support is "right and needed." She said Saturday she wanted Biden "to come to Ukraine in person and see the situation with his own eyes."
Maria Shevchenka, a 43-year-old from Mykolaiv, said that "we are waiting for them [the U.S.] to help us end this crisis, so that finally we can return back to our country and our homes."
More than 3.7 million people have fled Ukraine since the war began, and more than 2.2 million Ukrainians have crossed into Poland, though it is unclear how many have remained there and how many have left for other countries.
Earlier this week the U.S. announced it would take in as many as 100,000 refugees, and Biden told Duda that he understood Poland was "taking on a big responsibility, but it should be all of NATO's responsibility."