But tensions were mounting, with Kyiv's mayor announcing a 35-year curfew to deal with what he called a "dangerous moment", while Russia broadened its assault across Ukraine with a huge strike on an airport.
Nearly three weeks into Russia's invasion of its pro-Western neighbour, more than three million forced to flee to neighbouring countries and 97 Ukrainian children have died, the country's president told Canadian lawmakers in a virtual address.
In a response to crushing Western sanctions on Russia, Moscow announced that US President Joe Biden and a dozen other top officials had been banned from entering the country, criticising "the extremely Russophobic policy pursued by the current US administration".
According to the United Nations, nearly 1.4 million children have fled Ukraine since the conflict began on February 24 -- nearly one child per second. The UN High Commissioner for Human Rights has reported 1,834 civilian casualties.
Addressing a key Russian concern used to justify the invasion, Zelensky said Ukraine should accept that it would not become a member of NATO's military alliance.
"We have heard for years that the doors were open, but we also heard that we could not join. It's a truth and it must be recognised," he told a video conference with military officials.
Ukraine's capital has been transformed into a war zone, with apartment blocks badly damaged from Russian bombardments and half of the city's 3.5 million people now gone.
The 35-hour curfew will come into effect from 8:00 pm, the city's mayor Vitali Klitschko announced, saying that four died in the capital on Tuesday.
'Are you alive?'
"This is why I ask all Kyivites to get prepared to stay at home for two days, or if the sirens go off, in the shelters," he added.
Four large blasts were heard from the centre of the capital early Tuesday, sending columns of smoke high into the sky.
A fire raged in a 16-storey housing block and smoke billowed from the charred husk of the building, as emergency services and stunned residents navigated an obstacle course of glass, metal and other debris littering the road.
Another residential building in the Podilsk area also came under attack.
"At 4:20 everything was very thunderous, crackling. I got up, my daughter ran to me with a question: 'Are you alive?'," Lyubov Gura, 73, told AFP.
The district was once "a place to get coffee and enjoy life. Not anymore," Ukrainian MP Lesia Vasylenko said.
A Fox News cameraman, Pierre Zakrzewski, was killed and his colleague Benjamin Hall wounded when their vehicle was struck by incoming fire in Horenka, outside of Kyiv, on Monday, the US network announced.
Earlier on Tuesday, Ukrainian parliament's human rights chief said three other journalists had been killed since the invasion began, including a US reporter shot dead Sunday in Irpin, also on the outskirts of the capital.
Russian troops surround the city to the north and east, and authorities have set up checkpoints, while residents are stockpiling food and medicine.
Overnight Russian shelling also caused massive damage at the airport in the eastern Ukrainian city of Dnipro, regional authorities said.
"Two strikes. The runway was destroyed. The terminal is damaged. Massive destruction," said regional governor Valentin Reznichenko.
'Pretty good' talks
An AFP team saw large plumes of black smoke spewing out of the airport site but could not get closer as it was cordoned off by soldiers, who said the airport could be bombed again anytime.
In the besieged south-eastern city of Mariupol around 2,000 civilian cars managed to escape along a humanitarian evacuation route, local authorities said, following another 160 cars the previous day.
Outwardly, at least, the two sides are still far apart in negotiations, with Moscow demanding Ukraine turn away from the West and recognise Moscow-backed breakaway regions.
Ukraine is pushing for a ceasefire and Russian troop withdrawal. On Tuesday, Zelensky sounded a note of cautious optimism about ongoing peace talks and claimed Russia was realising victory would not come on the battlefield.
"They have already begun to understand that they will not achieve anything by war," Zelensky said.
He said Monday's talks were "pretty good... but let's see."
In an unprecedented show of solidarity with the embattled president, the Polish, Czech and Slovenian prime ministers took a train to Kyiv to meet Zelensky on Tuesday.
"In such crucial times for the world, it is our duty to be in the place where history is being made," Poland's Mateusz Morawiecki said in a Facebook post.
Russia's military progress has been slow and costly, with Moscow apparently underestimating the strength of Ukrainian resistance.
Western defence experts believe Russia's military now needs time to regroup and resupply its troops, paving the way for a possible pause or slowdown in fighting.
Fined and released
NATO worries that Russia is gearing up to carry out a chemical attack in Ukraine, secretary general Jens Stoltenberg said, citing "absurd claims" that Ukraine possesses biological weapons labs and warning that Russia would pay "a high price" if it did so.
On Tuesday, Chinese Foreign Minister Wang Yi said China does not want to be impacted by Western sanctions on Russia, as US pressure grows on Beijing to withdraw support from Moscow.
"China is not a party to the crisis, still less wants to be affected by the sanctions," Wang said.
Reports this week said Moscow had turned to Beijing for military and economic help -- prompting what one US official called "very candid" talks between high-ranking US and Chinese officials.
A Britain-based war monitor said Moscow had drawn up lists of 40,000 fighters from Syrian army and allied militias to be put on standby for deployment in Ukraine.
In the face of the assault, Kyiv's allies have piled economic pressure on Putin's regime, as Britain added 350 more Russians to its sanctions list, hiked tariffs on a swathe of imports from vodka to steel and banned exports of luxury goods.
A journalist who brandished -- in a brief but electrifying moment on live TV -- a slogan protesting the invasion of Ukraine was fined and released by a Russian court on Tuesday after pleading not guilty to violating demonstration laws.
Marina Ovsyannikova, the dissenting employee, barged onto the set of Russia's most-watched evening news broadcast on Channel One late Monday, holding a poster reading "No War".
Under Russian law, she had risked a maximum sentence of 15 years.
