Russia's key attack targets in Ukraine

• Russian troops moved in from the north toward Kyiv and from Crimea in the south, while affected regions in the east were Kharkiv and the two breakaway areas that Russian President Vladimir Putin declared "republics," Donetsk and Luhansk, per the BBC.

State of play: Heavy fighting was reported into Friday at the Gostomel airfield, just north of Kyiv, as Ukrainian officials raised concerns that the Russian army could use this as a launchpad to try and take Ukraine's capital.

• Russian tanks were reported to have entered Kharkhiv after shelling portions of Ukraine's second-largest city, huge explosions were heard in Donetsk and Russia-backed separatists claimed they'd begun attacking the Ukrainian-controlled town of Shchastia in Luhansk.
• Ukrainian officials reported on Thursday that Russian forces had seized control of the Chernobyl nuclear power plant.

Meanwhile, 13 Ukrainian border guards were killed after refusing to surrender Snake Island in the Black Sea to a Russian warship on Thursday.

By the numbers: A U.S. defense official told reporters Russia's military has fired over 160 missiles targeting Kyiv and other Ukrainian cities since Thursday, per the Washington Post.

Go deeper: Ukraine-Russia crisis dashboard

Editor's note: This article has been updated with details of the number of missiles launched by Russia and of fighting at the airfield.