One source was cited as saying that Kallas is seen as playing the role of a "bad cop" behind the scenes for EU member states, and even Rubio, despite his pro-European stances, declines bilateral meetings with the Estonian diplomat.
Since last week, the US has been promoting a new peace proposal for Ukraine and sent negotiators to Geneva on Sunday for talks with Ukraine. The original 28-point peace plan was subsequently revised down to 19 points, eliminating some of the initial proposals, such as downsizing Ukrainian armed forces, reducing US military aid and banning foreign military presence in Ukraine, as well as reportedly the recognition of Crimea and Donbas regions as Russian.
US media reported earlier in the day that US Army Secretary Daniel Driscoll is meeting with Russian officials in Abu Dhabi on Tuesday to discuss the new plan.
On November 21, Russian President Vladimir Putin said that Trump's new peace plan could form a basis for a final settlement in Ukraine.