First Thing: Biden and Putin exchange warnings amid Ukraine tensions – The Guardian

First Thing: Biden and Putin exchange warnings amid Ukraine tensions  The GuardianBiden and Putin exchange warnings over Ukraine  ReutersPutin Warns Biden of ‘Complete Rupture’ of U.S.-Russia Relationship Over Ukraine  The New York TimesBiden and Putin hold call over Russia-Ukraine tensions. What the U.S has at stake.  NBC NewsFive Things You Need to Know to Start Your Day  Bloomberg