A Ukrainian serviceman sits on the ground at combat positions on the outskirts of Kharkiv, Ukraine February 24, 2022. REUTERS/Maksim Levin

Russia is facing more resistance than Moscow anticipated in its invasion of Ukraine, including in its advance on the capital, Kyiv, and appears to have lost some of its momentum, a senior US defense official said on Friday.

Russian missiles pounded Kyiv on Friday, families cowered in shelters and authorities told residents to prepare Molotov cocktails to defend Ukraine’s capital from an assault that the mayor said had already begun with saboteurs in the city.

But the US official, who spoke on condition of anonymity, suggested a mixed picture for the Russian effort to press an offensive that Washington and Kyiv say is aimed at decapitating the government and installing a puppet regime.

“We do assess that there is greater resistance by the Ukrainians than the Russians expected,” the senior defense official said, adding Ukraine’s command and control of its military “remains intact”.

“They are not moving on Kyiv as fast as what we believe they anticipated they would be able to do. That said, they continue to try to move on Kyiv.”

Still, Russia has not yet mobilized the majority of its forces arrayed around Ukraine, the official said, assessing that just about one-third have now been “committed” to its offensive.

The official cited indications of a Russian amphibious assault west of Mariupol, “putting potentially thousands of naval infantry ashore there.” The United States had also observed more than 200 total missile launches so far.

Although most of the Russian targeting has been against Ukrainian military installations, some of the missiles have landed on civilian residential areas, the official said.

Ukraine’s military was putting up a fight, the official said.

“They are fighting for the country,” the official said, noting that Russia had yet to establish control of the airspace above Ukraine or used the extent of its electronic warfare capabilities.

“In general, the Russians have lost a little bit of their momentum,” the official said. The official said several hundred American citizens have left Ukraine over the past 24 hours.