Russia's invasion of Ukraine looks designed to take Kyiv and create a land corridor south to the Black Sea, splitting the country into two, military analysts and former officials said, echoing the view of Ukraine's generals.

President Vladimir Putin may still seek some form of control over the entire country, they said, as he strives to stop Ukraine ever joining NATO. He is also not guaranteed victory. A senior U.S. defense official said Friday that Russia was facing more resistance than it expected, not least in its advance on Kyiv.

The tactics of the advancing Russian troops point to a "flanking movement" from Ukraine's weakest points — its northern border with Belarus, and in the south Crimea, which Russian annexed eight years ago, with its huge naval base.