With the Kremlin increasingly isolated by tough economic sanctions that have tanked the ruble currency, Russian troops attempted to advance on Ukraine’s two biggest cities. In strategic Kharkiv, an eastern city with a population of about 1.5 million, videos posted online showed explosions hitting the region’s Soviet-era administrative building and residential areas.

Throughout the country, many Ukrainian civilians spent another night huddled in shelters, basements or corridors.

The casualty toll mounted as Ukraine faced Day 6 of a Russian invasion that has shaken the 21st century world order. Hopes for a negotiated solution to the war dimmed after a first, five-hour session of talks between Ukraine and Russia yielded no stop in the fighting, though both sides agreed to another meeting in coming days.

With Western powers sending weapons to Ukraine and driving a global squeeze of Russia’s economy, Russian President Vladimir Putin’s options diminished as he seeks to redraw the global map — and pull Ukraine’s western-leaning democracy back into Moscow’s orbit.

“I believe Russia is trying to put pressure [on Ukraine] with this simple method,” Ukrainian President Volodymyr Zelensky said late Monday in a video address.

He did not offer details of the talks that took place Monday, but he said Kyiv was not prepared to make concessions “when one side is hitting another with rocket artillery.”

The Kremlin has twice in as many days raised the spectre of nuclear war and put on high alert an arsenal that includes intercontinental ballistic missiles and long-range bombers. Stepping up his rhetoric, Putin denounced the United States and its allies as an “empire of lies.”

Meanwhile, an embattled Ukraine moved to solidify its ties to the West by applying to join the European Union — a largely symbolic move for now, but one that won’t sit well with Putin, who has long accused the United States of trying to pull Ukraine out of Moscow’s orbit.

A top Putin aide and head of the Russian delegation, Vladimir Medinsky, said that during the first talks held between the sides since the invasion, the envoys “found certain points on which common positions could be foreseen.” He said they agreed to continue the discussions in the days ahead.

The Russian military has denied targeting residential areas despite abundant evidence of shelling of homes, schools and hospitals.

The UN human rights chief said at least 102 civilians have been killed and hundreds wounded — warning that figure is probably a vast undercount — and Ukraine’s president said at least 16 children were among the dead.

What’s happening on the ground 

WATCH | CBC’s Margaret Evans reports from Kyiv, where people emerged from underground shelters to try and secure food and other critical supplies: 

Kyiv residents faced depleted supplies as negotiators meet

Kyiv residents emerged from shelters to a city landscape changed by war and running low on food. Russian and Ukrainian negotiators met to discuss a ceasefire over the sound of air raid sirens, but didn’t reach a resolution. 2:31

As the talks along the Belarusian border wrapped up, several blasts could be heard in Kyiv, and Russian troops advanced on the city of nearly three million. The convoy of armoured vehicles, tanks, artillery and support vehicles was 25 kilometres from the centre of the city, according to satellite imagery from Maxar Technologies.

People in Kyiv lined up for groceries after the end of a weekend curfew, standing beneath a building with a gaping hole blown in its side. Kyiv remained “a key goal” for the Russians, Zelensky said, noting that it was hit by three missile strikes on Monday and that hundreds of saboteurs were roaming the city.

“They want to break our nationhood, that’s why the capital is constantly under threat,” Zelensky said.

Messages aimed at the advancing Russian soldiers popped up on billboards, bus stops and electronic traffic signs across the capital. Some used profanity to encourage Russians to leave. Others appealed to their humanity.

“Russian soldier — Stop! Remember your family. Go home with a clean conscience,” one read.

Shelling hits residential areas in Kharkiv 

Ukrainian authorities say the centre of the country’s second-largest city has been hit by renewed Russian shelling.

Oleh Sinehubov, the head of the Kharkiv regional administration, said the administration building in the centre of Kharkiv came under Russian shelling Tuesday along with residential buildings. Sinehubov didn’t give any specific numbers of casualties from the latest shelling.

Previously, Sinehubov said at least 11 people were killed and scores of others were wounded in the shelling in Kharkiv on Monday. He said Ukrainian troops are fending off Russian attempts to advance on the city of roughly 1.4 million people.

Southern communities

In the seaside resort town of Berdyansk, dozens of protesters chanted angrily in the main square against Russian occupiers, yelling at them to go home and singing the Ukrainian national anthem. They described the soldiers as exhausted young conscripts.

“Frightened kids, frightened looks. They want to eat,” Konstantin Maloletka, who runs a small shop, said by telephone. He said the soldiers went into a supermarket and grabbed canned meat, vodka and cigarettes.

“They ate right in the store,” he said. “It looked like they haven’t been fed in recent days.”

The strategic port city of Mariupol, on the Sea of Azov, is “hanging on,” said Zelensky adviser Oleksiy Arestovich.

In a later Facebook post, he said many Russian soldiers and some local residents also were killed during the fighting on Sunday. The report could not immediately be confirmed. Despite its superior military strength, Russia still lacked control of Ukrainian airspace. This may help explain how Ukraine has so far prevented a rout.

-From The Associated Press and Reuters, last updated at 5:30 a.m. ET

For many, Russia’s announcement of a nuclear high alert stirred fears that the West could be drawn into direct conflict with Russia. But a senior U.S. defence official, speaking on condition of anonymity, said the United States had yet to see any appreciable change in Russia’s nuclear posture.

As far-reaching Western sanctions on Russian banks and other institutions took hold, the ruble plummeted, and Russia’s Central Bank scrambled to shore it up, as did Putin, signing a decree restricting foreign currency.

But that did little to calm Russian fears. In Moscow, people lined up to withdraw cash as the sanctions threatened to drive up prices and reduce the standard of living for millions of ordinary Russians.

In yet another blow to Russia’s economy, oil giant Shell said it was pulling out of the country because of the invasion. It announced it will withdraw from its joint ventures with state-owned gas company Gazprom and other entities and end its involvement in the Nord Stream 2 pipeline project between Russia and Europe.

The economic sanctions, ordered by the U.S. and other allies, were just one contributor to Russia’s growing status as a pariah country.

Russian airliners are banned from European airspace, Russian media is restricted in some countries, and some high-tech products can no longer be exported to the country. On Monday, in a major blow to a soccer-mad nation, Russian teams were suspended from all international soccer.