US vows ‘swift, severe and united response’ if Russia invades Ukraine

Anthony Blinken rejects calls for preemptive sanctions but says massive consequences' await as US orders families of embassy staff out of Kyiv

• The Biden doctrine: Ukraine tops mixed year of foreign policy

The US and its allies will deliver a swift, severe and united response" if Russia invades Ukraine, the secretary of state, Antony Blinken, warned on Sunday amid rising tensions.

The top US diplomat's comments came as Russia continued its military build-up on the Ukraine border and Britain said it had exposed evidence of a plot by Vladimir Putin to install a pro-Moscow government in Kyiv.