(NewsNation Now) — As Russian forces increased their shelling of Ukraine, President Volodymyr Zelenskyy appealed to the West to strengthen sanctions.

In a video statement Sunday evening, Zelenskyy criticized Western leaders for not responding to the Russian Defense Ministry’s announcement that it would strike Ukraine’s military-industrial complex, while telling employees of these defense plants not to go to work.

“I didn’t hear even a single world leader react to this,” Zelenskyy said. “The audacity of the aggressor is a clear signal to the West that the sanctions imposed on Russia are not sufficient.”

Zelenskyy called for organizing a “tribunal” to bring to justice those who order and carry out such crimes.

Russian troops shelled cities across Ukraine and a second attempt to evacuate civilians from a southern city under siege failed Sunday as Russia’s invasion stretched into its 11th day,

Interior Ministry adviser Anton Gerashchenko said a second effort to evacuate some of the 400,000 civilians from the port city of Mariupol along designated humanitarian corridors was halted because of an ongoing assault.

“There can be no ‘green corridors’ because only the sick brain of the Russians decides when to start shooting and at whom,“ he said on messaging service Telegram.

Evacuations were scheduled to begin at noon local time during a very tentative 10 a.m. to 9 p.m. local cease-fire, Ukrainian military authorities said.

With each side blaming the other for the cease-fire collapse, Russian President Vladimir Putin said in a phone call with Turkish President Tayyip Erdogan on Sunday his campaign in Ukraine was going according to plan and would not end until Kyiv stopped fighting.

The International Committee of the Red Cross (ICRC) blamed an insufficiently clear agreement between the two sides.

“Amid devastating scenes of human suffering in Mariupol, a second attempt today to start evacuating an estimated 200,000 people out of the city came to a halt,” the ICRC said in a statement.

A similar cease-fire planned there and in the nearby city of Volnovakha collapsed Saturday, trapping women, children and older residents under more shelling and aerial bombardment by Russian forces.

The head of the United Nations’ refugee agency says that more than 1.5 million refugees have crossed from Ukraine into neighboring countries since Russia invaded.

Filippo Grandi, the U.N. high commissioner for refugees, tweeted Sunday that it is “the fastest-growing refugee crisis in Europe since World War II.”

His agency didn’t immediately give a more precise update on the refugee figures. Grandi is visiting countries that border Ukraine.

Zelenskyy is pushing his call for foreign countries to impose a no-fly zone over Ukraine.

Establishing a no-fly zone would risk escalating the conflict by involving foreign militaries directly. Although the United States and many Western countries have backed Ukraine with weapons shipments, they have sent no troops.

Zelenskyy said in a video address Sunday that “the world is strong enough to close our skies.”

NATO countries have ruled out policing a no-fly zone, which would bar all unauthorized aircraft from flying over Ukraine. Putin said Saturday that Moscow would consider any third-party declaration of a no-fly zone over Ukraine as “participation in the armed conflict.”

Meanwhile, the U.S. and European allies are exploring banning imports of Russian oil, according to U.S. Secretary of State Antony Blinken.

Europe relies on Russia for crude oil and natural gas but has become more open to the idea of banning Russian products in the past 24 hours, a source familiar with the discussions told Reuters on Sunday.

The White House is also talking with the Senate Finance Committee and House of Representatives Ways and Means Committee about a potential ban, the source said.

Still, Blinken also stressed the importance of maintaining steady oil supplies globally.

Putin continued to blame the war on the Ukrainian leadership and slammed their resistance to the invasion. He said if they continued to resist, “They are calling into question the future of Ukrainian statehood.” His comments came as Zelenskyy made a “desperate plea” to the U.S. Congress for more planes as Russian forces continued to batter strategic locations.

U.S. Secretary of State Anthony Blinken said Washington was “very, very actively” considering how it could backfill aircraft for Poland, if Warsaw decided to supply its warplanes to Ukraine, speaking on a trip to neighboring Moldova.

Blinken said Sunday that the United States has seen “very credible reports” of deliberate attacks on civilians by Russians forces in Ukraine, and that Washington was documenting these reports to make sure relevant organizations can investigate whether war crimes have been committed.

Russian forces Sunday launched hundreds of missiles and artillery attacks across the country, including dropping powerful bombs on residential areas of Chernihiv, a city north of the capital of Kyiv, Ukrainian officials said. But a miles-long Russian armored column threatening the capital remained stalled outside Kyiv.

Zelenskiy on Sunday said Russian rockets had completely destroyed the civilian airport of the central-western region capital of Vinnytsia.

Earlier, the authorities said emergency services were working to put out fires at the airport caused by the rocket strikes.

Zelenskyy said Ukrainian forces were holding key cities in the central and southeastern part of the country, while the Russians were trying to block and keep encircled Kharkiv, Mykolaiv, Chernihiv and Sumy.

Ukrainian forces were defending Odesa, Ukraine’s biggest port city, from Russian ships, Ukrainian presidential adviser Oleksiy Arestovich said.

Russian troops took control of the southern port city of Kherson last week. Although they have encircled Kharkiv, Mykolaiv, Chernihiv and Sumy, Ukrainian forces have managed to keep control of key cities in central and southeastern Ukraine, Zelenskyy said.

Several media outlets reported Sunday that Russia is recruiting Syrian soldiers, who have grown accustomed to urban combat during that country’s long civil war.

Also Sunday, Turkish President Tayyip Erdogan urged Putin to declare a cease-fire, open humanitarian corridors and sign a peace agreement, his office said.

NATO member Turkey shares a maritime border with Russia and Ukraine in the Black Sea and has good ties with both. Ankara has called Russia’s invasion unacceptable and offered to host talks, but has opposed sanctions on Moscow.

In a statement after a one-hour phone call, the Turkish presidency said Erdogan told Putin that Turkey was ready to contribute to a peaceful resolution of the conflict.

“President Erdogan, who said an immediate ceasefire will not only ease humanitarian concerns in the region but also give the search for a political solution an opportunity, renewed his call of ‘let’s pave the way for peace together,'” his office said.

Israel’s prime minister says his country will continue to assist in finding a diplomatic solution to the Ukraine crisis, even if the chances for success are few.

Naftali Bennett spoke Sunday to a meeting of his Cabinet, hours after he returned from a surprise meeting with Putin in Moscow, where the two discussed the war with Ukraine. He then traveled to Germany where he met Chancellor Olaf Scholz.

Bennett revealed no details from his talks with Putin, but called the country’s mediation efforts “our moral duty.” Earlier, his office said he and Zelenskyy spoke by phone Sunday morning, the third such call between the two leaders over the past day.

Bennett also told his Cabinet that Israel was readying for a wave of Jewish immigration from Ukraine. Israel is also preparing to allow entry to a small number of non-Jewish Ukrainians fleeing the conflict.

Israel is one of the few countries that has good working relations with both Russia and Ukraine.

Across Russia, more than 2,500 people were detained at protests Sunday in 49 cities, according to an independent Russian-based protest monitoring group.

The Associated Press and Reuters contributed to this report.