WATCH: Pentagon press secretary John Kirby holds news briefing as fighting continues in Ukraine’s Donbas region

U.S. Pentagon officials say Russian President Vladimir Putin has “achieved exactly zero” of his strategic objectives as the Ukrainian city of Sievierodonetsk becomes the center of fierce fighting in the east.

Watch the briefing in the player above.

Pentagon Press Secretary John Kirby told reporters in Friday’s press briefing, “Our assessment is that the Russians continue to make some incremental gains in the Donbas. Not great magnitude — not leaps and bounds. They are facing and continue to face a stiff Ukrainian resistance.”

Sievierodonetsk’s Mayor Oleksandr Stryuk says it’s holding out even though a Russian reconnaissance and sabotage group went into a city hotel.

He said at least 1,500 people have been killed in Sievierodonetsk and about 12,000 to 13,000 remain in the city, where he said 60 percent of residential buildings have been destroyed.

Sievierodonetsk is the only part of the Luhansk region in the Donbas under Ukrainian government control, and Russian forces have been trying to cut it off from the rest of Ukrainian-controlled territory.

“They are facing and continue to face a stiff Ukrainian resistance, which is why I won’t go so far as to say it’s too late to provide the Ukrainians with any system or capability that they might need because they are very active in the fight,” Kirby said.

Ukrainian President Volodymyr Zelenskyy pleaded with the West on Thursday to send multiple launch rocket systems to Ukraine as soon as possible to give it a chance against the Russian offensive in the eastern Donbas.

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He said Russian forces are wiping some eastern towns from the face of the Earth and the region could end up “uninhabited.”

“We’re mindful and aware of Ukrainian asks, privately and publicly for what is known as a multiple launch rocket system, Kirby said.

“We’re working every single day to get weapons and systems into Ukraine. And every single day there are weapons and systems getting into Ukraine that are helping them literally in the fight.”

Meanwhile, Putin says that Ukraine should remove sea mines from areas near its ports to allow safe shipping.

The Russian president made the statement in Friday’s call with Austrian Chancellor Karl Nehammer, according to the Kremlin readout of the conversation.

It said that Putin and Nehammer “had a detailed exchange of views on issues regarding food security” with Putin rejecting Western claims that Russia’s action exacerbated a global food crisis.

“The world community is mindful of the weaponization of food that Mr. Putin is now doing, ” Kirby told reporters.

The Kremlin noted that “Putin emphasized that attempts to blame Russia for difficulties regarding shipments of agricultural products to global markets are unfounded.”

It added that the Russian leader “gave a detailed explanation of the real roots behind those problems that emerged, in particular, because of the U.S. and the EU sanctions against Russia.”

The U.S. and other Western allies have rejected the Russian demand for the sanctions to be lifted and accused Moscow of blocking grain supplies from Ukraine to global markets – accusations the Kremlin has denied.