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As Ukraine enters its third day of Russian bombardment following President Vladimir Putin’s invasion this week, a senior defense official said Saturday that Moscow has become “increasingly frustrated” by the lack of momentum.

“We have indications that the Russians are increasingly frustrated by their lack of momentum over the last 24 hours, particularly in the north parts of Ukraine,” the senior defense official said. “We also continue to see indications of viable Ukrainian resistance.”

RUSSIA INVADES UKRAINE: LIVE UPDATES

Ukrainian soldiers take positions outside a military facility as two cars burn, in a street in Kyiv, Ukraine, Saturday, Feb. 26, 2022.

Ukrainian soldiers take positions outside a military facility as two cars burn, in a street in Kyiv, Ukraine, Saturday, Feb. 26, 2022. (AP Photo/Emilio Morenatti)

“We continue to believe, based on what we’ve observed, that this resistance is greater than what the Russians expected,” the official added. 

Russian forces have entered Ukraine from the north, south and east, and defense officials believe Putin is attempting to encircle the capital city of Kyiv.

Russia launched a successful amphibious assault from the Sea of Azov Friday and its forces continue to make advancements, but the defense official said Russia has been unable to gain air superiority or take control over any Ukrainian cities.

Despite attempted advances, Russian forces have been unable to successfully penetrate Kyiv and remain approximately 20 miles outside the city.

UKRAINE-RUSSIA WAR: KYIV STILL STANDING ON DAY 3, ZELENSKYY REFUSES TO LEAVE COUNTRY

People take cover as an air-raid siren sounds, near an apartment building damaged by recent shelling in Kyiv, Ukraine February 26, 2022. 

People take cover as an air-raid siren sounds, near an apartment building damaged by recent shelling in Kyiv, Ukraine February 26, 2022.  (REUTERS/Gleb Garanich )

Though the official noted the situation in Ukraine is a “battlefield” and remains “very dynamic and will change hour by hour.”

The United Kingdom’s defense ministry said Saturday that the capture of Kyiv remains Putin’s primary objective, but said strong Ukrainian resistance and logistical difficulties have hindered Russian advancements. 

Overnight clashes that did occur in Kyiv are believed to have been carried out by small numbers of pre-positioned Russian sabotage groups. 

Intermittent internet outages persist in Ukraine and civilian housing has been hit largely by Russian shelling and explosives.

Russian troops are “bypassing” areas with large populations and are instead leaving forces behind to “encircle and isolate them,” the U.K. defense ministry said. 

Defense officials estimate that of the 150,000 troops Russia amassed along Ukraine in the months leading up to the incursion that more than 50% of those forces have already entered Ukraine. 

President Biden approved the distribution of another $350 million in military aid to Ukraine to help its continued fight against the Russian incursion – pushing U.S. defensive aid for Kyiv over the last year to $1 billion.

Ukrainian service members are seen at the site of a fighting with Russian raiding group in the Ukrainian capital of Kyiv in the morning of February 26, 2022,

Ukrainian service members are seen at the site of a fighting with Russian raiding group in the Ukrainian capital of Kyiv in the morning of February 26, 2022, (SERGEI SUPINSKY/AFP via Getty Images)

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Pentagon press secretary John Kirby told reporters Saturday this aid would come in the form of anti-armor, small arms, various munitions, body armor and “related equipment in support of Ukraine’s frontline defenders.”

“We, along with our allies and partners are standing together to continue to expedite security assistance to Ukraine,” Kirby said. “Our commitments and deliveries continue as a sign of our unwavering support for Ukraine sovereignty and territorial integrity.”