A senior U.S. defense official said the Pentagon does not assess that the Ukrainian port city of Mariupol has fallen to Russia, countering claims by President Vladimir Putin Thursday. 

"We don't assess that it is fallen to the Russians. The Ukrainians are still there, still resisting," a senior U.S. defense official said Thursday. "Mariupol still continues to fall victim to continued airstrikes from the Russians."

Smoke rises above a plant of Mariupol Azovstal Iron and Steel Works factory on Wednesday. 

Smoke rises above a plant of Mariupol Azovstal Iron and Steel Works factory on Wednesday.  (REUTERS/Alexander Ermochenko)

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The official said that roughly 1,670 Russian missiles have been levied at Ukrainian targets since the war began eight weeks ago, and the majority of missile launches are now focused throughout the Donbas region and in Mariupol.  

Mariupol is a strategically important port city, not only because of its access to the Sea of Azov and the direct coast-to-coast access it would grant Russia – but because of Moscow’s strategy for eastern Ukraine. 

Defense officials have said that Russia is planning to pinch the Luhansk and Donetsk region by invading from the north through Kharkiv and up from the south through Mariupol.

But despite weeks of intense shelling, Russia has been unable to completely besiege the southern city.

Putin claimed victory over Mariupol Thursday despite the fact that thousands of resistance fighters remain in the city holed up in tunnels deep under the Azovstal steel plant.

A Russian military convoy moves on a highway in an area controlled by Russian-backed separatist forces near Mariupol, Ukraine, Saturday, April 16, 2022. Mariupol, a strategic port on the Sea of Azov, has been besieged by Russian troops and forces from self-proclaimed separatist areas in eastern Ukraine for more than six weeks. 

A Russian military convoy moves on a highway in an area controlled by Russian-backed separatist forces near Mariupol, Ukraine, Saturday, April 16, 2022. Mariupol, a strategic port on the Sea of Azov, has been besieged by Russian troops and forces from self-proclaimed separatist areas in eastern Ukraine for more than six weeks.  (AP Photo/Alexei Alexandrov)

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Putin claimed that it would not be necessary to root out the resistance forces bunkered in and instead directed his troops to "block this industrial zone in such a way that even a fly could not fly through."

The senior U.S. defense official said Thursday that the U.S. is doing what it can to help Ukrainians in Mariupol short of having boots on the ground.

"We do provide the Ukrainians, every day, intelligence and information that we believe will be helpful for them, their ability to fight the Russians as well as to improve their defensive capabilities," the official said.

The U.S. approved another $800 million in security assistance Thursday that the senior defense official said was "strategically" planned with Ukrainian officials to help them with the fight in the Donbas. 

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Armed servicemen of Donetsk People's Republic militia look at a photographer as they carry captured weapons in an area controlled by Russian-backed separatist forces in Mariupol, Ukraine, Friday, April 15, 2022. Mariupol, a strategic port on the Sea of Azov, has been besieged by Russian troops and forces from self-proclaimed separatist areas in eastern Ukraine for more than six weeks. 

Armed servicemen of Donetsk People's Republic militia look at a photographer as they carry captured weapons in an area controlled by Russian-backed separatist forces in Mariupol, Ukraine, Friday, April 15, 2022. Mariupol, a strategic port on the Sea of Azov, has been besieged by Russian troops and forces from self-proclaimed separatist areas in eastern Ukraine for more than six weeks.  (AP Photo/Alexei Alexandrov)

Despite continued fighting in eastern Ukraine, U.S. officials have warned they do not believe Russia has actually begun its full assault in the area and is still conducting "shaping operations."

Roughly 85 Russian battalion tactical groups are believed to have entered eastern Ukraine.