Kamala Harris tells Ukrainian president that Moscow will face 'unprecedented economic costs' if it launches invasion; UK's Johnson urges Western unity against Russian threats

Amid raging Ukraine tensions, top diplomat indicates in meeting with Putin that Moscow is prepared to continue talks; UK leader Johnson warns invasion could come within 48 hours

British prime minister given seven days to fill out questionnaire regarding 'partygate' as calls grow for him to step down if found to have broken the law

UK's Johnson calls crisis most dangerous moment for continent in decades, dispatches soldiers to Poland as icy talks with Moscow flounder; Biden urges Americans to leave Ukraine

Biden's medical advisor says new treatments and vaccines will make virus 'more manageable'; UK's Johnson says measure to ditch isolations will only take effect if infections low

Chief of staff, principal private secretary, communications director and senior adviser resign over involvement in party held at Downing mid-pandemic

As police investigate breach of COVID regulations in PM's residence, partial findings of Sue Gray's report say behavior 'difficult to justify'

Law enforcement asks investigators to keep parts of crucial report unpublished due to investigation, sowing doubt about findings that could deliver heavy blow to prime minister

Britain awaits release of report into allegations Johnson and staff flouted COVID restrictions; public anger grows, with some Conservative lawmakers calling for PM's resignation

Commissioner says investigators looking at 'a number of events' over past two years, as reports surface of rule-breaking birthday party for PM in 2020