The latest as of 8:00 p.m. ET Sunday:

• Google Maps has temporarily disabled tools that provide live information about traffic conditions and how busy different places are in Ukraine due to safety concerns.
• A referendum in Belarus on Sunday approved a new constitution ditching the country’s non-nuclear status as the country has become launch pad for Russian troops.
• European Commission President Ursula Von Der Leyen told Euronews that the EU wants Ukraine to join the bloc, saying, “They’re one of us.”
• Brazilian President Jair Bolsonaro on Sunday declined to condemn Russia’s invasion of Ukraine, saying Brazil would remain neutral.

Ukraine’s president warned Sunday evening that the next 24 hours are crucial for the country facing a Russian invasion that is attacking from “all directions.”

President Volodymyr Zelenskiy gave the notice to U.K. Prime Minister Boris Johnson in a phone conversation, according to a Johnson spokesperson.

Ukraine’s armed forces said Sunday that the day has been a “difficult time” for the military and Russian troops “continue shelling in almost all directions,” a description also used by the Kremlin.

As Ukraine battles, Russian President Vladimir Putin ordered his nuclear-armed forces to be put on high alert, escalating fears of a nuclear war despite Ukraine confirming an agreement to hold talks with Moscow.

In giving the nuclear alert directive on Sunday, Putin cited “aggressive statements” by NATO members and wide-ranging economic sanctions imposed by the Western nations against Russia, including the Russian leader himself.

The alert means Putin has ordered Russia’s nuclear weapons prepared for increased readiness to launch — a move that was swiftly condemned by the United States.

“President Putin is continuing to escalate this war in a manner that is totally unacceptable, and we have to continue to stem his actions in the strongest possible way,” U.S. Ambassador to the United Nations Linda Thomas-Greenfield told CBS.

On Sunday, a referendum in Belarus approved a new constitution that ditches the country’s non-nuclear status, opening the door for nuclear weapons to be placed in the country for first time since it gave them up after the fall of the Soviet Union.

Meanwhile, there appeared to be some progress on the diplomatic front after Ukrainian President Volodymyr Zelenskyy’s office said delegations from both sides had agreed to a meeting at the Ukrainian-Belarusian border.

The talks, the first since Russia launched a full-scale invasion of Ukraine on Thursday, would be held without preconditions at an unspecified location on the Belarusian border, Zelenskyy’s office said in a statement on Sunday.

Zelenskyy, though, said that he doesn’t “really believe” in the outcome of the meeting but it is worth an attempt so there is no doubt that he “tried to stop the war.”

The U.N. Security Council has also approved an emergency session in the General Assembly on Monday concerning the invasion. As the council’s vote was procedural, Russia could not use its veto.

2:05
‘Nothing is off the table with this guy:’ U.N. Ambassador Linda Thomas-Greenfield on Putin

The announcement came as Russian forces rolled into Ukraine’s second-largest city of Kharkiv.

A fierce battle was underway Sunday in Kharkiv, where Russian troops blew up a natural gas pipeline before daybreak, according to the Ukrainian state agency.

“The Russian enemy’s light vehicles have broken into Kharkiv, including the city centre,” regional Governor Oleh Sinegubov said, urging civillians to remain inside.

Heavy fighting between Russian and Ukrainian forces erupted in Kharkiv following intensive overnight exchanges of rocket artillery, U.K.’s Ministry of Defense said in an update on Twitter.

7:42
Russia-Ukraine conflict: What is Putin’s endgame?

Until Sunday, Russian troops had remained on the outskirts of Kharkiv, a city of 1.4 million about 20 km (12.4 miles) south of the border with Russia, while other forces moved their offensive deeper into Ukraine.

Meanwhile, in the capital Kyiv, where a curfew has been extended until Monday, clashes have subsided and Ukrainian forces were resisting the Russian offence.

“Russian forces are continuing to advance into Ukraine from multiple axis (sp) but are continuing to be met with stiff resistance from the Ukrainian Armed Forces,” Britain’s defence ministry said.

As of Sunday, both Kyiv and Kharkiv remained in Ukrainian hands.

The conflict has created a swell of refugees at European borders, with queues at crossings stretching for kilometres and nearly 400,000 people seeking safety abroad.

After weeks of warnings from Western leaders, Putin launched the invasion of Ukraine on Thursday from the north, east and south.

Putin has justified the invasion, saying “neo-Nazis” rule Ukraine and threaten Russia’s security — a charge Kyiv and Western governments say is baseless propaganda.

Before invading, Putin had demanded that Ukraine not be allowed to join NATO. However, the conflict has since brought the country closer to NATO allies, with European Commission President Ursula Von Der Leyen also saying the EU would like Ukraine to join its bloc.

“They’re one of us,” she told Euronews.

For the first time since the start of the invasion, the Russian military said that some of its troops were killed and wounded in Ukraine, without mentioning any numbers.

Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov said Sunday that the Russian forces have hit 1,067 Ukrainian military facilities, including 27 command posts and communication centers, 38 air defense missile system and 56 radar stations.

At least 352 civilians, including 14 children, have been killed so far and 1,684 have been wounded, including 116 children, according to Ukraine’s health ministry.

Ukraine, for its part, has claimed that its forces killed 3,500 Russian troops.

Claims from both sides have not been independently confirmed.

Airspace ban

As Europe’s largest ground war since the Second World War rages on, a Russian delegation of military officials and diplomats arrived in neighbouring Belarus offering talks with Ukraine.

Zelenskyy said his country was open to peace talks but had earlier rejected Russia’s offer, saying Belarus had been complicit in the invasion and instead suggested alternative locations.

Putin hasn’t disclosed his ultimate plans, but Western officials believe he is determined to overthrow Ukraine’s government and replace it with a regime of his own, redrawing the map of Europe and reviving Moscow’s Cold War-era influence.

In response to the Russian aggression, the United States, Canada and other NATO allies have sent weapons and other aid to Ukraine, which is not a NATO member. Canada announced an additional $25 million in non-lethal aid and airlift support on Sunday, while the U.K. has opened £40 million more and Australia has promised US$3 million.

NATO allies have also slapped Russia with a string of economic sanctions, freezing the assets of Russian businesses and individuals including Putin and his foreign minister.

On Sunday, Canada, Germany, France, Spain and Italy joined the U.K., the Nordics and Baltic states in shutting their airspace to Russian planes.

“Effective immediately, Canada’s airspace is closed to all Russian aircraft operators,” Canada’s Transport Minister Omar Alghabra said on Twitter

“We will hold Russia accountable for its unprovoked attacks against Ukraine.”

— with files from Reuters and the Associated Press