US pledges more help for Ukraine as Russian troops move to encircle Kyiv

Hours after Russia's strike on a military base near Ukraine's border with Poland, the U.S. has pledged to supply the Ukrainian government with more weapons and security assistance.

Moscow is already threatening to target foreign weapons shipments headed to Ukraine. And facing calls for more drastic measures like a no-fly-zone, the Biden administration says it won't take any actions that increase the risk of direct conflict with Russia.

Jennifer Johnson reports.