KYIV, Ukraine (AP) — Russia escalated its bombardment of the Ukrainian capital and launched new assaults on the port city of Mariupol, making bloody advances on the ground as Ukraine’s president prepared Wednesday to make a direct appeal for more help in a rare speech by a foreign leader to the U.S. Congress.An elderly woman is helped by policemen after she was rescued by firefighters from inside her apartment after bombing in Kyiv, Ukraine, Tuesday, March 15, 2022. Russia’s offensive in Ukraine has edged closer to central Kyiv with a series of strikes hitting a residential neighborhood as the leaders of three European Union member countries planned a visit to Ukraine’s embattled capital. (AP Photo/Felipe Dana)© Provided by Associated Press An elderly woman is helped by policemen after she was rescued by firefighters from inside her apartment after bombing in Kyiv, Ukraine, Tuesday, March 15, 2022. Russia’s offensive in Ukraine has edged closer to central Kyiv with a series of strikes hitting a residential neighborhood as the leaders of three European Union member countries planned a visit to Ukraine’s embattled capital. (AP Photo/Felipe Dana)As the invasion entered its third week, Ukrainian President Volodymyr Zelenskyy suggested there was still some reason to be optimistic negotiations might yet yield an agreement with the Russian government.

After their delegations met Tuesday via video, Zelenskyy said Russia’s demands were becoming “more realistic.” The sides were expected to speak again later Wednesday.

“Efforts are still needed, patience is needed,” he said in his video address to the nation. “Any war ends with an agreement.”

Developments on the diplomatic front and on the ground occurred as the number of people fleeing Ukraine amid Europe’s heaviest fighting since World War II eclipsed 3 million.

Zelenskyy, previewing his speech to the U.S. Congress, thanked President Joe Biden and “all the friends of Ukraine” for $13.6 billion in new support.

He appealed for more weapons and more sanctions to punish Russia and repeated his call to “close the skies over Ukraine to Russian missiles and planes.”

Military cadets attend a funeral ceremony for four of the Ukrainian military servicemen, who were killed during an airstrike in a military base in Yarokiv, in a church in Lviv, Ukraine, Tuesday, March 15, 2022. At least 35 people were killed and many wounded in Sunday's Russian missile strike on a military training base near Ukraine's western border with NATO member Poland. (AP Photo/Bernat Armangue)© Provided by Associated Press Military cadets attend a funeral ceremony for four of the Ukrainian military servicemen, who were killed during an airstrike in a military base in Yarokiv, in a church in Lviv, Ukraine, Tuesday, March 15, 2022. At least 35 people were killed and many wounded in Sunday’s Russian missile strike on a military training base near Ukraine’s western border with NATO member Poland. (AP Photo/Bernat Armangue)He said Russian forces on Tuesday had been unable to move deeper into Ukrainian territory but had continued their heavy shelling of cities.

Over the past day, 28,893 civilians were able to flee the fighting through nine humanitarian corridors, although the Russians refused to allow aid into Mariupol, he said.

Also Tuesday, the leaders of three European Union countries — Poland, the Czech Republic and Slovenia — visited Kyiv in a bold show of support amid the danger.

Russia’s bombardment of the capital appeared to become more systematic and edged closer to the city center Tuesday, smashing apartments, a subway station and other civilian sites. Zelenskyy said the barrages hit four multi-story buildings and killed dozens.

A senior U.S. defense official, speaking on the condition of anonymity to discuss the Pentagon’s assessment, said the Russians were using long-range fire to hit civilian targets inside Kyiv with increasing frequency but that their ground forces were making little to no progress around the country. The official said Russian troops were still about 15 kilometers (9 miles) from the center of the capital.

The official said the U.S. has seen indications that Russia believes it may need more troops or supplies than it has on hand in Ukraine, and it is considering ways to get more resources into the country. The official did not elaborate.

Before Tuesday’s talks, Russian Foreign Minister Sergey Lavrov said Moscow would press its demands that Ukraine drop its bid to join NATO, adopt a neutral status and “demilitarize.”

In a statement that seemed to signal potential grounds for agreement with Moscow, Zelenskyy told European leaders gathered in London that he realizes NATO has no intention of accepting Ukraine.

“We have heard for many years about the open doors, but we also heard that we can’t enter those doors,” he said. “This is the truth, and we have simply to accept it as it is.”

NATO does not admit nations with unsettled territorial conflicts. Zelenskyy has repeatedly said he realizes NATO isn’t going to offer membership to Ukraine and that he could consider a neutral status for his country but needs strong security guarantees from both the West and Russia.

The U.N. said close to 700 civilians in Ukraine have been confirmed killed, with the true figure probably much higher.

Two journalists working for Fox News were killed when the vehicle they were traveling in was hit by fire Monday on the outskirts of Kyiv, the network said. Fox identified the two as video journalist Pierre Zakrzewski and Ukrainian journalist Oleksandra “Sasha” Kuvshynova, who was helping Fox crews navigate the area. Another journalist was killed Sunday in Ukraine.

New efforts to bring civilians to safety and deliver aid were underway. The Red Cross said it was working to evacuate people in about 70 buses from the northeastern town of Sumy, near the Russian border.

The exodus from Mariupol marked the biggest evacuation yet from the southern city of 430,000, where officials say a weekslong siege has killed more than 2,300 people and left residents struggling for food, water, heat and medicine. Bodies have been buried in mass graves.

Kyrylo Tymoshenko, a senior aide to Zelenskyy, said about 20,000 people managed to leave Mariupol on Tuesday in 4,000 private vehicles via a designated safe corridor leading to the city of Zaporizhzhia.

People attend a funeral ceremony for four of the Ukrainian military servicemen, who were killed during an airstrike in a military base in Yarokiv, in a church in Lviv, Ukraine, Tuesday, March 15, 2022. At least 35 people were killed and many wounded in Sunday's Russian missile strike on a military training base near Ukraine's western border with NATO member Poland. (AP Photo/Bernat Armangue)