President Volodymyr Zelenskyy says he is no longer pressing for NATO membership for Ukraine, a delicate issue that was one of Russia's stated reasons for invading its pro-Western neighbour.
In another apparent nod aimed at placating Russia, Mr Zelenskyy said he is open to "compromise" on the status of two breakaway pro-Russian territories that President Vladimir Putin recognized as independent just before unleashing the invasion on 24 February.
"I have cooled down regarding this question a long time ago after we understood that ... NATO is not prepared to accept Ukraine," Mr Zelenskyy said in an interview aired on Monday night on America's ABC News.
"The alliance is afraid of controversial things, and confrontation with Russia."
Referring to NATO membership, Mr Zelenskyy said through an interpreter that he does not want to be president of a "country which is begging something on its knees."
The announcement marked a major shift in Ukraine's stance which had previously been a leading sore point in relations between Russia on one side, and NATO and Ukraine on the other.
Russian President Vladimir Putin has pressed on with his war despite unprecedented sanctions, although Russia agreed to open humanitarian corridors from four Ukrainian cities on the 13th day of the conflict.
The number of refugees flooding across Ukraine's borders to escape towns devastated by shelling and air strikes has passed two million, in Europe's fastest-growing refugee crisis since World War Two, the UN said.
Buses streamed out through an evacuation corridor from the north-eastern city of Sumy — where 21 people were killed in air strikes overnight.
Civilians on foot meanwhile, took an unofficial escape route out of the bombarded Kyiv suburb of Irpin.
But Ukraine accused Russia of attacking a corridor from the beleaguered southern port city of Mariupol, where aid workers said tens of thousands of people were living in "apocalyptic" conditions.
Ukraine has branded the corridors a publicity stunt as many of the exit routes lead into Russia or its ally Belarus. Both sides accuse each other of ceasefire violations.
Evacuated children from an orphanage in Hulaipole at the train station in Lviv, western Ukraine, on 7 March 2022. Source: EPA, AAP / Vitaliy Hrabar
Russia has warned that oil sanctions would have "catastrophic consequences".
But the US has led the push for energy sanctions — partly because Russia accounts for less than 10 per cent of US imports of oil and petroleum products, which means the impact on the world's largest economy would be easier to bear.
Mr Biden said the ban had been decided "in close consultation" with allies, especially those in Europe, who depend on Russia for 40 per cent of their gas needs.
US rejects Poland offer of jets for Ukraine as not 'tenable'
The US has rejected a Polish offer to send MiG-29 fighter jets to Ukraine via a US air base, saying the proposal raised "serious concerns" for the entire NATO alliance.
Poland caught US officials off guard with the offer to deliver the Soviet-era planes to the US base in Ramstein, Germany.
Under the proposed scheme, those jets could then be deployed to Ukraine, while the Polish air force would receive F-16 fighters as replacements.
Pentagon spokesman John Kirby said the prospect of the jets, placed at the disposal of the United States, flying from a US-NATO base "into airspace that is contested with Russia over Ukraine raises serious concerns for the entire NATO alliance."
"We will continue to consult with Poland and our other NATO allies about this issue and the difficult logistical challenges it presents, but we do not believe Poland's proposal is a tenable one," Mr Kirby said in a statement.
"It is simply not clear to us that there is a substantive rationale for it," he added.
MiG-29 fighter jets at 22nd Air Base Command in Malbork, Poland on 27 August, 2021. Source: Getty / Anadolu Agency
Ukraine has stepped up calls for Western allies to supply it with military jets in the face of the Russian invasion, but providing Ukraine with war planes poses serious risks — with NATO members unwilling to be deemed co-combatants by Russia.
Ukraine's air force fleet consists of aging Soviet-era MiG-29 and Sukhoi-27 jets, and heavier Sukhoi-25 jets — and these are the only planes Ukrainian pilots could fly immediately without additional training.
US Secretary of State Antony Blinken said during a visit to Moldova on Sunday the US government was "actively" looking at a deal with Poland to provide Ukraine with the MiG-29s.
But after Poland announced its offer, US Undersecretary of State for Political Affairs Victoria Nuland told US lawmakers that Washington had been caught off guard.
Asked by a senator whether US officials coordinated ahead of time with Poland, Nuland said: "Not to my knowledge."
While several lawmakers pressed for the jets to be rushed to Ukraine, Nuland refused to commit the US to supporting or facilitating the exchange.
"I will continue to convey the very strong bipartisan view of this committee that these planes need to get to Ukraine," she told the panel.
"There are a number of factors to consider here and there are some mixed views among allies and even within the administration."
While a significant part of Ukraine's air force remains intact since the war began on February 24, both Ukraine and Russia have sustained significant losses and neither controls the airspace over the country.
'Hiding in the basement'
Russian troops are slowly encroaching on Kyiv despite intense efforts by outgunned Ukrainian forces, and moving faster through the east and north of the country.
Despite the sound of nearby shelling in Irpin, seen as a critical point for the advance on the capital, civilians fled in icy wind and thick snowfall, reporters from news agency AFP saw.
People waited in a long line to cross over the Irpin river on makeshift walkways of planks and mangled metal, after the Ukrainians blew up the bridge leading into the capital to hamper any Russian advance.
"I didn't want to leave, but there's nobody left in the homes around us, no water, no gas and no electricity," Larissa Prokopets, 43, told AFP.
She said she was leaving after several days spent "hiding in the basement" of her home, which kept "shaking" due to bombardment nearby.
Russia had refused calls for a humanitarian corridor in Irpin and the nearby suburbs of Bucha and Gostomel "although we had everything ready for this", Ukrainian interior ministry official Anton Gerashchenko said.
Evacuations had however begun in Sumy, near the Russian border and 350 kilometres east of Kyiv, where Russia had formally declared a humanitarian corridor, officials said.
Dozens of buses had already left in the direction of Lokhvytsia, to the southwest, with the corridor designed to evacuate civilians, including Chinese, Indians and other foreigners, officials said.
The evacuation came after 21 people, including two children, were killed in Sumy overnight. Three people were killed and three children wounded by a landmine in Chernihiv, north of Kyiv, officials said.
People sit around a lamp in a bomb shelter in Mariupol, Ukraine, on Sunday, 6 March, 2022. Source: AAP, AP / Evgeniy Maloletka
'Alone, exhausted, frightened'
Ukraine's defence ministry also accused Russia on Tuesday of violating a ceasefire to ease a days-long blockade of Mariupol, describing it as "genocide".
A six-year-old girl identified only as Tanya died from dehydration under the rubble of her destroyed home in Mariupol, the city council said.
"In the last minutes of her life she was alone, exhausted, frightened and terribly thirsty," Mayor Vadym Boychenko said.
Mr Zelenskyy denounced what he called unkept promises by the West to protect his country, and renewed calls for a no-fly zone that leaders have so far dismissed.
"It's been 13 days we've been hearing promises, 13 days we've been told we'll be helped in the air, that there will be planes," Mr Zelenskyy said on a video broadcast on Telegram.
Evacuation efforts of Irpin, Ukraine, continued through adverse weather conditions on 8 March, 2022. Source: SIPA USA, AAP / Justin Yau
Addressing the British parliament on Tuesday, he reiterated his demands for more support from the West as he delivered a defiant speech invoking former UK prime minister Winston Churchill's resistance against Nazi Germany during World War II.
"We will fight to the end, at sea, in the air. We will continue fighting for our land, whatever the cost, in the forests, in the fields, on the shores, in the streets," Mr Zelenskyy said before receiving a standing ovation.
Global outrage has mounted over the invasion and the plight of civilians caught up in the bloodshed.
The International Committee of the Red Cross (ICRC) said Mariupol residents faced "atrocious" conditions and were running out of food, water and medical supplies.
"The bottom line today is that this situation is really apocalyptic for people," ICRC head of media Ewan Watson said in Geneva.
At least 474 civilians have been killed since the start of Russia's assault on its ex-Soviet neighbour, according to the UN, although it believes the real figures to be "considerably higher".
