US increasingly concerned by Russian military threat to Ukraine

• President Zelenskiy warns of escalation' in east of country
• Angela Merkel urges Vladimir Putin to scale down troop buildup

The US has said it is increasingly concerned over Russian militarisation along Ukraine's border, as the Ukrainian president, Volodymyr Zelenskiy, travelled to the eastern frontline.

The number of Russian troops at the border with the former Soviet republic is now greater than at any time since 2014", when war in eastern Ukraine first broke out and Russia seized the Crimea region, the White House press secretary, Jen Psaki, said in Washington.