US and EU 'united' over Russia
26 March 2014 Last updated at 23:11 GMT
The US and EU have warned Russia will face "deeper sanctions" if there are "further incursions into Ukraine".
US President Barack Obama met EU leaders for talks in Brussels.
Tensions are high between the West and Russia after Ukraine's southern peninsula of Crimea was annexed by Russian forces earlier this month.
Matthew Price reports from Brussels.