KYIV, Ukraine — Russian forces called in air strikes on a besieged steel factory in the southern city of Mariupol as part of an assault meant to dislodge the last Ukrainian troops holding out in the strategic port, Ukrainian officials said Sunday, while President Volodymyr Zelenskyy said he would meet in Kyiv with two top American officials later in what was the 60th day since the invasion began.

Zelenskyy gave few details about the logistics of his upcoming talks with U.S. Secretary of State Antony Blinken and U.S. Defense Secretary Lloyd Austin, but told reporters he expected results — “not just presents or some kind of cakes, we are expecting specific things and specific weapons.”

It would be the first high-level U.S. trip to Kyiv since before the war began on Feb. 24. While visiting Poland in March, Blinken stepped briefly onto Ukrainian soil to meet with the country’s foreign minister. Zelenskyy’s last face-to-face meeting with a U.S. leader was Feb. 19 in Munich with Vice President Kamala Harris.

In Mariupol, Russian forces have continued to pummel the besieged Azovstal plant, hitting it with air strikes, including by long-range aircraft, Oleksandr Shtupun, spokesman for the Ukrainian Armed Forces General Staff, said Sunday.

Russia has been trying to take Mariupol for nearly two months, a city whose capture would deprive Ukraine of a vital port, free up Russian troops to fight elsewhere, and establish a land corridor to the Crimean Peninsula, which Moscow seized in 2014. Russia-backed separatists control parts of the Donbas region, where Mariupol is located.

Some 2,000 troops have been fighting tenaciously to hold on to the last remaining Ukrainian outpost in the city, the Azovstal steel plant, which also has civilians taking refuge in its labyrinthine tunnel system.

Russian President Vladimir Putin had given an order not to send troops in but instead to blockade the plant last week, but the assault resumed Saturday after the Ukrainian soldiers refused to surrender.

Elsewhere, Shtupun said Russia has pressed its attacks in the eastern Donbas region, intensifying offensive and assault operations toward the cities of Popasna and Siverodonetsk in Luhansk, and Kurakhiv in Donetsk.

Luhansk region Governor Serhiy Haidai said Sunday that eight people were killed and two others were wounded in a Russian barrage Saturday.

The shelling comes as the Russians are pressing their offensive in a bid to gain full control over Ukraine’s eastern industrial heartland called Donbas.

The Russians also have shelled the Dnipro region west of Donbas, where at least one person was killed by a Russian missile, according to Dnipro regional Governor Valentyn Reznichenko.

Russia has pulled back forces from Kyiv and the north of the country to feed into the Donbas offensive, but the British Ministry of Defense said Sunday that Ukrainian forces had been able to repel numerous assaults in the past week.

“Despite Russia making some territorial gains, Ukrainian resistance has been strong across all axes and inflicted significant cost on Russian forces,” the ministry said in an intelligence update.

“Poor Russian morale and limited time to reconstitute, re-equip and reorganize forces from prior offensives are likely hindering Russian combat effectiveness,” it said.

The Ukrainian military said Saturday it destroyed a Russian command post in Kherson, a southern city that fell to Russian forces early in the war.

The command post was hit on Friday, killing two generals and critically wounding another, the Ukrainian military intelligence agency said in a statement. The Russian military did not comment on the claim, which could not be confirmed.

If true, at least nine Russian generals have been killed since the start of the invasion, according to Ukrainian reports.

The fate of the Ukrainians in the sprawling steel mill in Mariupol, where Russia says its forces have taken the rest of the city, wasn’t immediately clear.

On Saturday the Azov Regiment of Ukraine’s National Guard, which has members holed up in the plant, released a video of around two dozen women and children. Its contents could not be independently verified, but if authentic, it would be the first video testimony of what life has been like for civilians trapped underground there.

The video shows soldiers giving sweets to children who respond with fist-bumps. One young girl said she and her relatives had “seen neither the sky nor the sun” since they left home Feb. 27.

The regiment’s deputy commander, Sviatoslav Palamar, told the AP the video was shot Thursday. The Azov Regiment has its roots in the Azov Battalion, which was formed by far-right activists in 2014 at the start of the separatist conflict in eastern Ukraine and has elicited criticism for some of its tactics.

More than 100,000 people — down from a prewar population of about 430,000 — are believed to remain in Mariupol with scant food, water or heat. Ukrainian authorities estimate that over 20,000 civilians have been killed in the city.

Yet another attempt to evacuate women, children and older adults from Mariupol failed Saturday. Petro Andryushchenko, an adviser to Mariupol’s mayor, said Russian forces did not allow Ukrainian-organized buses to take residents to Zaporizhzhia, a city 227 kilometers (141 miles) to the northwest.