New Delhi, Feb 25 (IANS): The Pentagon believes Russia's invasion is designed to "decapitate" the Ukrainian government and install new leadership, a senior defense official told reporters on Thursday, Axios reported.

Russia's invasion — air, land and sea — is proceeding along three primary axes, with one of those aimed squarely at the capital, Kyiv, the official said.

Ukraine's ambassador to Washington told reporters that fighting is ongoing near Kyiv but the city is currently "secure".

Russian and Ukrainian troops battled for control of an airport near Kyiv on Friday, with Russian forces telling CNN they now control it. Russia is also invading from the north along the Belarusian border, which at its closest point is less than 100 miles from Kyiv.

The defence official said the heaviest fighting so far had been in Kharkiv, a city of 1.4 million nearly the border with Russia in the east, Axios reported.

Russian forces are also attacking from the south. Ukrainian President Volodymyr Zelensky said the "most problematic situation" was currently Russia's push north from Crimea.