Walker - Nato entered uncharted territory on Tuesday when one of its members, Turkey, shot down a Russian warplane.
There is an urgent need for Washington to bring both sides together to avoid World War Three.
18:16 Erdogan says Turkey will review EU ties after April referendum20
16:23 Tillerson’s next challenge: Reassuring senators on Russia over lunch18
11:04 Gorsuch begins his confirmation hearings Monday with broad support among Republicans19
07:48 Assad ally Russia summons Israeli diplomat over Syria strike19