Ukraine President Volodymyr Zelenskyy continued to call on the U.N. to do more in their struggle to fend off Russian aggressors, going as far as to accuse the West of cowardice during an address on Sunday.

Zelenskyy called for additional fighter jets and tanks as Russia pivots its focus on taking over the Donbas region in Eastern Ukraine.

“I’ve talked to the defenders of Mariupol today. I’m in constant contact with them. Their determination, heroism and firmness are astonishing,” Zelenskyy said in the address. “If only those who have been thinking for 31 days on how to hand over dozens of jets and tanks had 1% of their courage.”

The Associated Press contributed to this report.

Ukrainian and Russian officials will meet on Monday in Istanbul for the next round of in-person peace talks, a Ukrainian negotiator said Sunday.

Turkish President Recep Tayyip Erdoğan spoke with Russian President Vladimir Putin on Sunday to discuss the negotiations. 

"Stressing the need for the immediate establishment of ceasefire and peace between Russia and Ukraine as well as the amelioration of the humanitarian situation in the region, President [Erdoğan] said that [Turkey] would continue to lend every kind of support regarding the process," Turkish Presidency's communications office said Sunday.

Read more: Russia and Ukraine to start next round of live negotiations in Turkey in the coming days

Richard Engel, NBC News' chief foreign correspondent, told Chuck Todd on Sunday's "Meet The Press" that he doesn't believe Ukrainian President Volodymyr Zelenskyy was "overly impressed" with President Biden's comments in Poland about Russian President Vladimir Putin. 

Engel told Todd that the "Russian military strategy is all over the place." He said the strike on Lviv, a Ukrainian city 50 miles from the Polish border, was also likely meant to be a message to Biden.

"A bit of an insult to say ‘we’re going to strike right near the Polish border while you're in Poland," Engel said.

Read more: NBC News correspondent says Zelenskyy not 'overly impressed' by Biden's comments on Putin

Ukrainian President Volodymyr Zelenskyy accused the West of cowardice as his country fights to stave off Russia’s invading troops, making an exasperated plea for fighter jets and tanks to sustain a defense as the war ground into a battle of attrition.

Speaking after U.S. President Joe Biden said in a lacerating speech that Russian President Vladimir Putin could not stay in power — words the White House immediately sought to downplay — Zelenskyy lashed out Sunday at the West’s "ping-pong about who and how should hand over jets" and other weapons while Russian missile attacks kill and trap civilians.

"I’ve talked to the defenders of Mariupol today. I’m in constant contact with them. Their determination, heroism and firmness are astonishing," Zelenskyy said in a video address, referring to the besieged southern city that has suffered some of the war’s greatest deprivations and horrors. "If only those who have been thinking for 31 days on how to hand over dozens of jets and tanks had 1% of their courage."

Read more: Zelenskyy: West needs more courage in helping Ukraine fight

Kyiv Mayor Vitali Klitschko detailed the latest situation on the ground in the capital of Ukraine during an exclusive interview on "Sunday Morning Futures," telling host Maria Bartiromo that soldiers in the country are showing a "big will" to win the war. 

Klitschko, a former heavyweight boxing champion, called on the West to offer more support to help Ukraine and said that experts told him that the war could last for months.

"Nobody knows, and that’s why we have to be prepared for any scenario," Klitschko said.

Klitschko made the comments as Russian forces appear to have shifted their focus from a ground offensive aimed at Kyiv, to instead prioritizing what Moscow calls liberation of the contested Donbas region in the country’s industrial east, officials said on Friday. 

The mayor of Kyiv said the situation in the capital city "changes every day" and that in the "last 24 hours was pretty quiet compared to last week." 

Read more: Kyiv Mayor Klitschko: Ukraine soldiers 'show big will to win this fight'

Ukraine's Ministry of Defence accused Russian forces of using banned cluster munitions against civilians, sparking an investigation.

"Another day, another russian war crime. Yesterday it was Krasnohorivka near Donetsk. Today the russians used banned cluster munitions against civilians near Kryvyi Rih," the Ministry of Defence tweeted Sunday.

The tweet added that an investigation has been launched those allegedly behind the attack "will face the tribunal."

AP Photo/Geert Vanden Wijngaert

French President Emmanuel Macron  warned against escalation Sunday regarding Ukraine, a day after President Biden said Russian President Vladimir Putin was a "butcher" who "cannot remain in power." 

"I wouldn't use this type of wording because I continue to hold discussions with President Putin," Macron said Sunday during an appearance on France 3 TV channel. "We want to stop the war that Russia has launched in Ukraine without escalation -- that's the objective."

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Russian soldiers are taking cellphones from Ukrainian civilians to speak to one another and call family back home, according to a European intelligence official.

The Russian soldiers' conversations on Ukrainian civilians' phones have revealed a morale drop as they continue their invasion of the country, according to the anonymous official.

The official said that some Russian commanders have also taken their subordinates’ personal phones to prevent them from giving away a unit's location, the official told the Washington Post.

Ukrainian Presidential Press Office via AP

A representative of President Volodymyr Zelenskyy described signatories to the Budapest Memorandum as a reason Ukraine is at war, citing their failure to hold up their end of the agreement.

"They signed their obligation to protect Ukraine, to provide the security and safety," Fedir Venislavsky, President Zelenskyy's representative to Ukraine's Constitutional Court, told Fox News. 

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Mike Coppola/Getty Images

Actor Sean Penn threatened to "smelt" his Oscars if Ukrainian President Volodymyr Zelenskyy isn’t asked to speak at the Academy Awards. 

"If it comes back to it, I will smelt [my Oscar awards] in public," Penn told CNN on Saturday afternoon. "I pray that’s not what’s happened. I pray there have not been arrogant people, who consider themselves representatives of the greater good in my industry, that have [decided against checking] with leadership in Ukraine."

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Finland suspended its train services with Russia, closing the rail link between Russia and the European Union, according to a Ukrainian official.

"No more rail connection for #Russia with #Europe: Finland suspends commercial, passenger and cargo rail services with Russia," Ukrainian Member of Parliament Lesia Vasylenko tweeted Sunday.

Finland's national railway operator announced services would be suspended between Helsinki and St. Petersburg Friday, saying the move would be carried out Monday.

Russia's defence ministry said Sunday high-precision cruise missiles hit the western Ukrainian city of Lviv.

"The armed forces of the Russian Federation continue offensive actions as part of the special military operation," the ministry's spokesman Igor Konashenkov said in a statement.

Long-range missiles hit a fuel depot near Lviv and cruise missiles struck a plat that was being used by Ukrainian forces to repair anti-aircraft systems and radar stations, the ministry said.

Secretary of State Antony Blinken clarified the U.S. is not seeking regime change in Russia.

The clarification comes a day after President Biden said during a speech in Warsaw, Poland, that Russian President Vladimir Putin "cannot remain in power.”

Blinken said during a news conference in Jerusalem that Biden’s point was “Putin cannot be empowered to wage war or engage in aggression against Ukraine or anyone else.”

“We do not have a strategy of regime change in Russia, or anywhere else for that matter,” the top U.S. official added.

And: “In this case, as in any case, it’s up to the people of the country in question. It’s up to the Russian people."

The Associated Press contributed to this report.

Sen. Tom Cotton criticized President Biden's current strategy for helping Ukraine: "We're still not doing everything we could do."

"We still could be sending them those S-300 systems to protect their airspace, for instance, or harpoon anti-ship missiles, coastal batteries that could destroy Russian ships just like they did the other day with one ballistic missile," the Republican added.

And: "These things should have been happening months ago, but it was really the bravery and the skill of the Ukrainian army and the leadership of President Zelenskyy that forced the hand of Western leaders to include Joe Biden to finally do what we should have done months ago."

FILE - Anti- tank barricades are placed on a street as preparation for a possible Russian offensive, in Odesa, Ukraine, March 24, 2022. The Black Sea port is mining its beaches and rushing to defend itself from a Mariupol-style fate. Some Western officials believe the city, which is dear to Ukrainians' hearts, could be next. (AP Photo/Petros Giannakouris, File)

Russian warships have moved closer, in provocation, to Odesa, Ukraine, Western officials said.

A potential attack on or seizure of Odesa could allow Moscow to build a presence in the region that could have a direct route to to the separatist Trans-Dniester region of Moldova, where a Russian military base is located.

A nearby bombardment has the Pentagon suspicious about the possibility of such an attack.

“It’s difficult to know what this indicates,” Pentagon press secretary John Kirby said of the latest bombardment. “Is it the prelude to an assault on Odesa? Is it a diversionary tactic to sort of hold and fix Ukrainian troops in the south so that they can’t come to the relief of their comrades in Mariupol or in Kyiv?"

Ukrainian authorities are confident Russia lacks the forces necessary to launch a swift offensive on Odesa.

The Associated Press contributed to this report.

Ukraine President Zelenskyy renewed calls for Western allies to provide weapons and military equipment to aid in their war with Russia.

"That is what our partners have, that is what is just gathering dust there. This is all for not only the freedom of Ukraine, but for the freedom of Europe," he said during an address Saturday evening, Reuters reported.

The Ukrainian leader called for NATO to supply just 1 percent of it's arsenal to help, but said that NATO nations were dissuaded by Russian "intimidation."

"We've already been waiting 31 days. Who is in charge of the Euro-Atlantic community? Is it really still Moscow, because of intimidation?" he added, per the report.

Ukraine President Volodymyr Zelensky awarded the Hero of Ukraine title to 15 servicemen, three posthumously, according to a report.

Governor Maksym Kozytskyy of Lviv, Ukraine says a suspect has been detained on suspicion of espionage near where a rocket attack occurred on Saturday.

Kozytskyy said the suspect sent location information to two Russian telephone numbers, the Associated Press reported.

In a tweet on March 26, President Biden said the U.S. would accept 100,000 Ukrainian refugees.

He added: “The people of Ukraine can count on the United States to meet its responsibility” to continue to help the country.

The announcement comes as the U.S. has "sent $650 million in weapons to Ukraine — and since, we have committed to another $1.35 billion," Biden added. 

Ukrainian forces have liberated Poltavka and Malynivka in the Zaporizhzhia Oblast, the Kviv Independent reported.

Both villages saw heavy fighting, according to the report.

Fox News' Arthel Neville gets reaction to President Biden’s Warsaw speech from a member of Ukrainian Parliament.

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